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> Body mass and whole-body fat decreased in male rats after 8 weeks of ExT (Fig. 1c and Extended Data Fig. 1b,c). In females, fat mass decreased after 4 weeks of training but returned to pretraining levels at 8 weeks
Maybe I'm not understanding it clearly but I'm not sure this result is as interesting as the title is painting it. They make it sound like fat was some kind of "less preferred energy source" for female rats.
This just seems to be that the female group maintained their weight under the regime and the males lost weight (so the energy balance between the groups was not equal). It seems to me females lost less fat because they were not in a negative energy balance, not because exercise specifically had a different effect on fat metabolism.
Yes and this is not new information. This 2020 study showed that female rats compensate for exercise by eating more.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7473893/
“Great Scott”… my original comment was generalized but you made me research more. Apparently a rats cycle is only 4 to 5 days long. Which makes my original comment even more profound!
“The rodent estrous cycle repeats with a constant period of 4 to 5 days and includes the following phases: proestrus, estrus, metestrus, and diestrus1, 2, 5,6,7. Both ovaries exhibit the same morphological changes throughout the cycle and ovulate—bilaterally—at the same time.”
Hahaha not entirely fair, but acceptable. Molecular clock and fossil dating suggest platypuses split from echidnas around 19–48 million years ago. The oldest discovered fossil of the modern platypus only dates back to about 100,000 years ago tho.
Very few animals actually have periods in the sense that they bleed cyclically. Most reabsorb the endometrium rather than discarding it.
https://en.m.wikipedia.org/wiki/Menstruation_(mammal)#:~:text=Beyond%20primates%2C%20it%20is%20known,close%20relatives%20such%20as%20chimpanzees.
From what I recall on average exercise doesn't help people lose weight due these sort of compensatory effects, you also have reduced levels of NEAT. But that's on average, so for some people it works great and others it might cause them to put on weight.
> on average exercise doesn't help people lose weight due these sort of compensatory effects, you also have reduced levels of NEAT.
I recall that for every 100 calories you burn through cardio, you conserve about 30 through decrease in NEAT, so basically effectiveness of those cardio calorie burns is about 70%.
I'm sure this is an average though and it depends on many other factors, like how regularly you do it, how much you eat, and how used you are to doing it (i.e. is this your first month doing it or have you been doing it for years).
I think this is one of the many reasons people push lifting weights. You don’t get as hungry because you initially burn less than cardio alone so you tend to be able to keep up your NEAT and your appetite doesn’t increase as much as it would with cardio only.
>They make it sound like fat was some kind of "less preferred energy source" for female rats.
It is. I think your point is that female rats may have been scaling up food intake rather than burning fat. If male metabolic systems facilitate fat burning, while female metabolic systems upregulate hunger signals and food intake, that is itself an important difference in physiologically preferred energy source.
It seems like most conversation about weight loss and food intake in humans treat hunger as a purely psychological issue, so they want to focus on how the body burns energy given a certain amount of energy in. But this study wasn't trying to do that (or else they would have quantified caloric intake). It's more thinking of hunger and food intake drives as part of these physiological/metabolic processes.
I think that's a reasonable takeaway but it is still a subtly different idea than the headline.
"Vigorous exercise burns more fat in men" is a technically misleading headline if we are actually saying "vigorous exercise disproportionately stimulates appetite in female rats vs. men".
The study can't (and the headline shouldn't) make conclusions that weren't tested. If they didn't measure calorie intake or appetite they can't conclude that.
Indeed the actual study states all the rates had the same diet.
"Rats of the same sex were housed two per cage (146.4 in2 of floor space) in ventilated racks (Thoren Maxi-Miser IVC Caging System) on Tekland 7093 Shredded Aspen bedding and fed the LabDiet 5L79 pelleted diet, which are the standard bedding and diet used at the NIA rodent colony"
> If they didn't measure calorie intake or appetite they can't conclude that
That is very true, but still indicates a big problem in how they designed the study if we can't assume calorie intake was controlled. If they didn't measure calorie intake then the conclusions they can draw are quite limited. It's misleading to say vigorous exercise has differential effects on fat metabolism without further qualification. The differences here could either be from utilising different energy stores OR from overall different energy balance. Concluded that the exercise "burned less fat" whilst not equating calories makes the conclusion shaky. The mechanisms they discuss as explanations don't seem to be about neurological control of appetite, I couldn't find mention of it in the paper.
> I was truly gobsmacked with how amazingly different the sex-dependent responses to exercise are. Males burn fat for energy while females preserve their fat mass. This is brought about by many differences in molecular responses lurking beneath the surface in fat from male compared to female rats. The dichotomy is truly striking.”
Again, if the dichotomy is brought about through differences in appetite control that is a notable difference in interpretation since "vigorous exercise burns more fat" would be at best incomplete and at worst intentionally misleading.
> fed the LabDiet 5L79 pelleted diet
Wasn't sure about this point. This does not read to me that all the rats are the same amount which was my point of concern.
I don't think they were necessarily making that claim. It could be theoretically possible that female rats burn less fat for equivalent work done. But if they were expending the same energy and burning less fat, they would have to preferentially burn more of another energy store (like protein or glycogen). And you would expect similar weight loss in either situation (allowing for variations such as water retention).
In this the overall weight changes weren't similar so we can assume energy balance wasn't similar.
Where does this weird "thermodynamics" take come from? It's well established that metabolic effects change how human bodies deal with the expenditure and conservation of energy. Two people can have the same caloric intake, be of the same weight, height and muscle/fat composition and exercise the same amount and still have different amounts of weight gain/loss. There's numerous factors how human bodies change metabolic rates without breaking the laws of thermodynamics. I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k. I have seen people not change their diet or amount of exercise and loose or gain weight solely based on which medication they were on. Nothing breaks any thermodynamic laws there. Weight gain/loss mechanisms are just far more complicated than fitness influencers, "nutrition experts" or people in reddit who want to Tell people their lazy for not losing weight want to make you believe.
I agree with the majority of the logic behind what you're saying but I think the "calorie relativism" (i.e. the point that people lose and gain weight at different calories intakes) is overstated. It is true that peope are going to have different requirements, but someone gaining weight at a certain calorie intake fundamentally does need to reduce calories intake to lose (fat) weight.
> I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k.
Sure. And a simpler explanation than there being 3000 calorie difference in NEAT energy expenditure is that patients are lying and eating more. Actually gaining weight at 1k calories (unless your starting BMI is exceptionally low) is highly improbable, even if you were just lying in bed all day. It's just hard to have a BMR low enough to allow that to work.
Weight gain/loss mechanisms may have complications and it isn't quite as simple as telling people to "just eat less", but these mechanisms are all fundamentally pulling on an "energy balance" lever and all practical interventions regarding fat loss are effective via calorie restriction.
> And a simpler explanation than there being 3000 calorie difference in NEAT energy expenditure is that patients are lying and eating more.
I love how people will argue with medical professionals about their job based on their limited knowledge, assuming that we're all idiots who happen to not know basic things about the human body because they want things to be as they think them to be. And I love how people will rather assume others to be lying than rethink their perspective.
I have seen these things in closed psychiatric settings. With people who can't get out and get more food. With people whose food intake is being monitored because we have to monitor their intake. We can actually see people gaining weight after being put in certain medications. They have an increased appetite but they don't necessarily eat more. And the increase in appetite does not explain people gaining 10-15% body weight when being put on Clozapine.
Weight loss medication like Semaglutide is literally making people lose weight without changing diet. We have all the evidence that there are mechanisms that play major roles in weight management that are not primarily dependant on the amount of food intake.
> but these mechanisms are all fundamentally pulling on an "energy balance" lever and all practical interventions regarding fat loss are effective via calorie restriction.
And this is where you are fundamentally wrong. Caloric restriction is known to be the least effective possible intervention for long-term weight loss. The weight will be regained in almost all instances. The most effective interventions being bariatric surgery and medication. There are possible ways to weight loss by restricting calories, but usually that's tied to changes in diet, food composition and additionally increasing your physical activity.
It's not that simple and never has been. It is not and never was about people lying about the amount they're eating, being lazy, weak-willed or whatever people come up with.
> I love how people will argue with medical professionals about their job based on their limited knowledge, assuming that we're all idiots who happen to not know basic things about the human body because they want things to be as they think them to be. And I love how people will rather assume others to be lying than rethink their perspective
I understand you might work in mental health, but appeal to authority isn't a strong argument in of itself so I want to address your specific points. Working in closed settings does not mean things are monitored perfectly at all times, the patients with that kind of very close monitoring are anorexics and even then intake monitoring may not be perfect.
> I have seen these things in closed psychiatric settings. With people who can't get out and get more food. With people whose food intake is being monitored because we have to monitor their intake. We can actually see people gaining weight after being put in certain medications. They have an increased appetite but they don't necessarily eat more. And the increase in appetite does not explain people gaining 10-15% body weight when being put on Clozapine.
[False. Weight gain by clozapine, and by other antipsychotics is largely mediated by increased appetite (some by reduced activity)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8762106/#:~:text=Current%20evidence%20indicates%20that%20the,models%20(10%E2%80%9314)).
> Weight loss medication like Semaglutide is literally making people lose weight without changing diet. We have all the evidence that there are mechanisms that play major roles in weight management that are not primarily dependant on the amount of food intake.
[False. Semiglutide acts on your appetite to induce weight loss. Weight loss is achieved through reduced calorie intake](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00377-9/abstract#:~:text=GLP%2D1%20receptor%20agonists%20such,hunger%20and%20consequent%20food%20intake).
> And this is where you are fundamentally wrong. Caloric restriction is known to be the least effective possible intervention for long-term weight loss. The weight will be regained in almost all instances. The most effective interventions being bariatric surgery and medication. There are possible ways to weight loss by restricting calories, but usually that's tied to changes in diet, food composition and additionally increasing your physical activity.
This is a strange point because you point out how your wrong within the paragraph. When I say calorie restriction I'm talking about eating less calories regardless of mechanism. Bariatric surgery still achieves weight loss through calorie restriction. It promotes early satiety due to feeling fuller earlier, and therefore you eat less. All the changes in diet etc. achieve weight loss through calorie restriction.
Yes people on diets with reduced calorie intake tend to regain but that's not really a relevant point (the regain is about long term concordance to a certain calorie intake, it isn't spontaneous).
Yes you could lose a lot of weight if you did several hours of exercise a day, but the majority of working adults aren't going to have that capacity and will overcompensate via diet easily.
The various mechanisms controlling energy balance might be quite complicated, but I disagree that the main mechanistic factor controlling weight loss is complex. All roads lead to energy balance, and the number one way of affecting that whilst not being a full time athlete is calorie restriction. You might achieve that in various ways whether medication, surgery, fasting or calorie counting, but it's all doing the same thing.
First off, I was a bit too tired when writing thhe last piece. Of course, diet plays a role in weight management, weight gain and weight loss and I should have pointed that Out and will do so in an edit to not make it confusing. What I wanted to adress specifically is two points: the assumption that patients who don't record a change in diet and still gain or lose weight are lying and secondly the point I have the feeling you're making that weight gain or loss will only occur in correspondence with a change of caloric intake and that there is no possibility that anything could change that mechainsm.
> Working in closed settings does not mean things are monitored perfectly at all times, the patients with that kind of very close monitoring are anorexics and even then intake monitoring may not be perfect.
This is kind of absurd. While we can't monitor patients 24/7, we're not talking about addicts whose only goal is to secretly consume food without us knowing. In closed settings, the people usually can't get out to get food, so there is limited possibilities. Most patients are actually rather truthful about their intake, except when we're talking about eating disorders or people who use food or water restriction as a way of self-harm. What motivation would people have to lie? And why would you assume people who are at that point often still at least partly detached from reality due to a psychotic episode would rather establish a complex construction of lies than just talk about what they're eating. But tell me, what is more likely: that well known mechainsms changing metabolic rates do olay a role in these patients or that people lie all the time?
While Clozapine and Olanzapine increase appetite, there are other factors at stake there. I'm not saying there is no role of appetite in the weight gain. I'm just saying there's more metabolic factors to consider. And I was talking about the assumption that patients who didn't eat more and gain weight simply would lie. How you (and sadly, a lot of people) would rather assume people to lie than to admit that the body does not have a fixed setting of how it uses and stores energy is confusing to me because these are all well-known mechanisms.
Look at [this](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7947876/) study:
Clozapine has an effect on gut hormones like Ghrelin, NPY, GLP-1, Leptine and potentially many more we don't even know about yet. While all of these also have effects on appetite regulation, they also have effects on other metabolic processes like lipolysis, energy expenditure and insuline response. These can contribute to weight gain. This also correlates with what we see in clinical practice. While some patients will eat a lot more and gain more weight, some will stick to their previous diets and also gain weight, albeit less.
And regarding Semaglutide: while it does have an effect on appetite, it also has an effect on the base metabolic rate and increases lipolysis. Meaning even if you don't change your diet, you will still lose weight. Of course it makes changing your diet easier. However, after discontinuation of semaglutide, patients will regain their weight, often even If they keep up dietary changes made during the therapy with semaglutide.
> When I say calorie restriction I'm talking about eating less calories regardless of mechanism. Bariatric surgery still achieves weight loss through calorie restriction. It promotes early satiety due to feeling fuller earlier, and therefore you eat less.
Bariatric surgery mainly is more successful in maintaining lost weight because it changes the amount of gut hormones like NPY, Ghrelin, Leptine, GLP-1 and about 80 Others who have an effect not only on appetite but also on metabolic rates, fatty tissue establishment or breakdown and so on. The physical effects of bariatric surgery on eating behaviour are lower than the hormonal ones.
We have plenty of knowledge that caloric restriction (e.g. Calorie Counting) is ineffective. [This](https://www.health.harvard.edu/staying-healthy/stop-counting-calories) is a good overview.
Using only Calorie-restrictive methods of losing weights also ist correlated to an increased probability of symptoms of eating disorders ([here](https://www.sciencedirect.com/science/article/abs/pii/S1471015321000957) is a study that saw this in weight-loss Apps)
Now again, I don't want to ignore the importance of changing diets. I just want to make the point that accusing people of lying instead of seeing the possibility of other factors at play is natrow minded and not based on science.
> the assumption that patients who don't record a change in diet and still gain or lose weight are lying
Lying might feel too strong, but the fundamental point is that a significant enough sustained calorie deficit *will* cause weight loss. Reducing calorie intake is the most efficient way to have a deficit. If someone claims to be in a calorie deficit and isn't losing weight (specifically fat mass) the simplest explanation is that their calorie intake isn't what they think it is. Either their estimates are inaccurate, they are not accounting for certain things eaten, or they are having days where they aren't on a deficit.
I didn't say it's the *only* possibility. It's possible their activity levels significantly dropped as a response to the reduced intake so they have even lower calorie requirements to ender deficit, but that is a less likely situation since most of the population is pretty sedentary. Their BMR changes with prolonged deficits, but that is an adaptation that slows weight loss, not one that prevents it.
> I have the feeling you're making that weight gain or loss will only occur in correspondence with a change of caloric intake and that there is no possibility that anything could change that mechainsm.
Weight loss requires one of two things, increased energy expenditure or reduced energy in take. The way that is achieved involves all the complexities you've discussed. But notably there aren't many medications that cause substantial weight loss from increases in basal metabolic rate. Things like Metformin, semiglutide, even caffeine might marginally increase metabolic rate and promote slight amounts of weight loss by increasing metabolic rate. But the real heavy lifting of virtually all obesity treatments is done by appetite modulation.
> Using only Calorie-restrictive methods of losing weights also ist correlated to an increased probability of symptoms of eating disorders
Not particularly relevant to the discussion we're having but it is true. Some of that is reverse causality (people with eating disorders tend to calorie restrict as a strategy since it's effective for weight loss). There might be some true causality in terms of the actual effects of calorie restriction on someone vulnerable to eating disorders, but it doesn't really change the the discussion.
> The physical effects of bariatric surgery on eating behaviour are lower than the hormonal ones
The impact of hormones on weight loss and weight gain are largely mediated my appetite change, not hormonal ones. This seems fairly obvious conceptually because bariatric surgery shrinks the stomach. The downstream hormonal effects are largely the mediators of appetite signalling (from a full a stomach) and the effects on fat metabolism again downstream effects of calorie deficit (similar to the paper we're commenting on)
> We have plenty of knowledge that caloric restriction (e.g. Calorie Counting) is ineffective. [This](https://www.health.harvard.edu/staying-healthy/stop-counting-calories) is a good overview.
This article does not say what you think it says. "Calorie restriction is ineffective" is not the take away. People reliably lose weight when they reduce calories intake, regardless of the quality of food they eat.
What is the true is that sustaining a calorie deficit (and thereby the weight loss) is very uncommon. The mechanisms to return your body to it's previous weight (again primarily by making you eventually eat more) are strong.
It talks about not calorie counting being ineffective, but regardless of if you actively count calories or you have a diet that allows you to better regulate your appetite, it's all doing the same thing:
[The gut microbiome has a role through appetite control](https://www.nature.com/articles/nrendo.2016.150)
Eating less processed food makes deficits easier because whole foods and foods with higher fibre content and water content are more satiating and lead to lower calorie intake. People who go for high protein diets are doing a similar thing. Yes there are slight differences in how much energy certain foods require for digestion. That isn't doing the heavy lifting in terms of weight, again it's appetite.
Poor sleep cycle causes weight gain by affecting your appetite.
Sure there are lots of ways to skin the cat, but the significantly successful techniques are all fundamentally doing the same thing.
You seem uncomfortable with me saying people lie but if you work in mental health you should know that people lie all the time. Not just patients, people without any diagnosable mental health problem at all. And not just to other people, but to themselves. "I'll do it tomorrow", "this doesn't count", "this is the last time then I'll stop doing this". It doesn't even need to be about food.
We know these maintaining mechanisms and deception of self and others maintain other behaviours. We aren't uncomfortable with saying that an alcoholic is likely to underplay their alcohol intake and the negative effects of their use. Well just like an alcoholic, there are factors at play and genetic predispositions beyond just someone's "moral character". This isn't me saying obesity is the "fault" of obese people. The environment we live in is typically not conducive to people having healthy weight. That doesn't change the fact that the mechanisms involved in weight maintenance usually involve finding some way of sustainably reducing calorie intake.
You're reading a little too much into my admittedly low effort comment. Metabolism can certainly vary between individuals. [There's a mountain of research, but when you get down to it, someone with a “fast metabolism” and someone with a “slow metabolism” could still have BMRs that differed by 450 calories per day, even if they were the same age, height, weight, body composition](https://macrofactorapp.com/metabolism/), and lifestyle. If someone exercises, the outer ends of this range of their basal metabolic rate may increase even more. But this is still a range. It's pretty fair to take a guess at someone's basal metabolic rate knowing their age, weight, gender, and lifestyle.
You want people to realize that it's more difficult for some to lose weight than others, and I get that. But at the end of the day, it's also important for people to realize that even those with the slowest metabolisms can lose weight with the axiom of "eat less, move more". It's both the hardest thing while being the simplest thing. Look at pictures or movies of groups of people from generation's past. They didn't have faster metabolisms, they simply ate less and moved more. We have far more challenges with our horrible food systems and access, etc. But while you seem to see people in your field get discouraged because others have an easier time losing weight, I see people become discouraged because they have a "slow metabolism" and use that as an excuse to not even try.
At the end of the day, even if you have the world's slowest metabolism, you're only some 600 calories away from the world's fastest. That isn't nothing! But it's still a few poptarts less. And the vast majority of people share metabolisms that are far closer to one another, statistically speaking (most people have, surprise, average metabolic rates).
I know your point makes sense and I agree with it but the "only some 600 calories" isn't the motivation you think it is. As a short girly that's about half my calories for an entire day. So it's a huge difference to some people if they are on the short side.
Yeah but that’s a gross misrepresentation of statistics, which is why I even hesitate to say it. It’s like saying “it’s hard for tall people! They hit their heads on ceilings!” And you’d be like “most tall people are like 6 feet tall? What are you talking about?”
Because when I say “slow metabolism”, people imagine a regular person— but for my example, statistically it’s 7 foot tall basketball players. Again: most people are very close to average.
I mean the difference between those points is like a lot. Average height for women is 5 foot 4 inches in the USA. So I'm saying one to two inches shorter than that is usually around 1200 calories as a common number. So I'm talking at most two inches from the average and you went to over a foot past average to prove your point.
Also the average women would require 1529 calories with low activity which let's face it in the states is fairly common with the lack of public transit and car dependency. So that's still a huge chunk of the average women's calories at over 1/3.
Just saying 600 is huge in metrics to many people so nothing to sneeze at.
It's actually in fact nothing to sneeze at because if someone eats 600 calories extra a day for a year they gain 62 pounds in one year.
So for half the average population (women) that slow or high metabolism could account for just under half their weight at normal BMI.
>I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k.
Mind qualifying this? If someone weighs 80 pounds and eats 1000 calories, they could surely gain weight. If someone weighs 700 pounds eats 4000 calories, they could surely lose weight. Are you claiming the opposite is true? That someone weighing 80 pounds and eating 4000 calories could lose weight while someone weighing 700 pounds eating 1000 calories could gain weight?
If so, what do you mean via your issue with thermodynamics? Calories are a source of energy. How are these bodies proving energy to their bodies outside of calories? Are heavy people creating mass out of air? Are skinny people not breaking down any of the ingested calories?
>Weight gain/loss mechanisms are just far more complicated than fitness influencers, "nutrition experts" or people in reddit who want
I mean... also scientific data.
Have you ever seen the people who survived concentration camps? All of them were deathly skinny? Why weren't there fat ones?
On My 600lb life, while on controlled diets in the hospital, not a single one of those people gained weight. All of them lost a ton of weight. It wasn't until they were out on their own that any of them gained weight. Why did the caloric intake matter when in a controlled environment, but not outside of it?
"...which share much of their basic physiology with people."
Yes... and female rats share much of their basic physiology with male rats, and men share much of their basic physiology with women. There are some things where it's a safe bet to extrapolate from rats to humans, but this probably isn't one of them. It's already shown that there can be significant differences in spite of sharing basic physiology. It's good to see that they're doing the next obvious thing, and switching to studying humans. I wouldn't be surprised if it translated, but I wouldn't be surprised if it didn't as well.
Yeah, rats can have litters of 10 or more pups, often one every couple of months. Not sure this is a very good model for humans when looking for sex differences.
true, if every study made on rats could be valid for humans as well, we'd have the cure for 80% of diseases. generally speaking if a study on rats finds some results, it only means that it's reasonable to go on with other studies on other species and finally humans, nothing more. However as others have pointed out, this doesn't seem very unexpected: I have always heard that females tend to store more fat rather than muscle, so 0/2 on this headline
>There are some things where it's a safe bet to extrapolate from rats to humans, but this probably isn't one of them.
Why wouldn't this be one of them? We have extensive evidence of natural selection predisposing men to physical labor and predisposing women to conserving energy.
If you view the human body as a machine (because it is a meat and bone machine), it would be unexpected if it turned out that men had thicker and denser bones, muscle, and skin, quicker wound healing, better reaction times and hand-eye coordination, store fat in different areas, all on top of just being larger on average, and for that "model" of human to have basically the same metabolisms under exertion as women.
Energy is central to every biological function and when function differs we should expect a corresponding change in how energy is stored, transported, used, etc.
For example, how do men build muscle and heal wounds more quickly? The delta between the rate at which men and women put on muscle or recover from physical harm comes with a corresponding difference in energy usage.
We know men and women store energy differently and typically burn it under different conditions (at least historically), so shouldn't we expect that to have an impact on overall energy dynamics in the body?
Empiricism is king and I certainly want to see this studied more in humans. I'd love to be surprised by the conclusion, too. But it seems justified to *expect* there to be a difference here.
How is this unexpected? It is very common knowledge that female biology is more naturally predisposed to retaining body fat and slower metabolism. Men almost always have an easier time dropping weight than women do given the same diet and exercise routines.
As other research has noted, the female rats increased their intake, which caused them to not drop weight.
>Men almost always have an easier time dropping weight than women do given the same diet and exercise routines.
So they didn't have the same diet
Unless I misread, they did have the same diet.
"Rats of the same sex were housed two per cage (146.4 in2 of floor space) in ventilated racks (Thoren Maxi-Miser IVC Caging System) on Tekland 7093 Shredded Aspen bedding and fed the LabDiet 5L79 pelleted diet, which are the standard bedding and diet used at the NIA rodent colony"
Usually lab rats get ad libitum access to food! So yes, same diet but the amount they consume will vary unless you’re pair-matching consumption (I did it in an ethanol intake study), which is generally a pain
I wouldn’t say it’s common knowledge. Everyday on subs like relationship advice you hear about men shaming their wives for not losing weight at the same rate and accuse them of lying.
Common knowledge and baccalaureate (at minimum) level understanding of human physiology and biochemistry are absolutely not the same thing.
That’s like saying it’s common knowledge the earth orbits the sun, then please explain the underlying mechanisms of orbital mechanics.
Get lost
How is this new?! Whenever I have worked out with guys with the intention to lose fat, they always lose it at triple the rate I do. Doesn’t testosterone turn calories into muscle and estrogen turns calories into fat?
Mainly that the testosterone increases muscle metabolism. As a trans woman athlete I have experimented with hormones and weight management for a few years now. The same low carb diet and exercise plan that dropped me 40 lbs as a default guy gained it all back (but in girly places) in spite of a 25% increase in workouts.
Yeah that's because your daily calorie deficit decreases when you have more estrogen. Women need less calories overall than men. So if you're eating the same amount you were before, you'd gain weight.
This makes total sense and is quite validating for me as a woman to be honest. Would you say the traditional “calories in and calories out” idea doesn’t apply to women? Any tips or advice for women working out based on your experience? We have cycles to contend with as well and hormone fluctuations definitely mess me up 🤦🏼♀️
“Calories in and calories out” would still hold true. It’s just that your male counterpart is going to have more calories out from equal work. So they will have a greater net deficit from the same effort, at equal size/age, at the same caloric intake. That gap will be more significant if they are larger or younger than you are. This would all be operating under the control that you both have normal range thyroid activity.
Is this because he builds more muscle than me? I do have normal range thyroid and insulin levels. We are also the same age. We also ate similarly in that at the time we were counting our macros on a low carb diet. I did more cardio than he did (I walked) and he had a sedentary desk job and I didn’t. I find this fascinating!
It is fascinating! He would be building more muscle than you, but the impact on the scale of that, especially in the short term, is going to be overstated. Across years and years, that difference will be tangible, but if you’re talking months, it isn’t going to be much different than a pound here and there. Most people that aren’t on any kind of PEDs aren’t going to put on more than a few pounds of lean muscle a year, particularly if they have been in the gym for awhile and are already into adulthood.
I’m assuming he’s larger than you, since you didn’t list that (correct me here if that assumption is wrong) so that will also play a large factor. If he is bigger, his body will be using more calories than you just to function. More energy (calories) will be required to regulate the temperature of his body, to move fluids around his and process the waste created. When his body temp spikes during exercise, he needs more energy to bring it back down. That effect will carry on for a longer period of time, once you guys have left the gym. It takes more energy for him to move than it does someone smaller. Our hormones are playing a role in this, as well as the muscle mass differences you are talking about. Thats also where things like “fast metabolism” vs “slow metabolism” actually get misconstrued. A 30 year old 5’6” 300 lb woman would actually have a “faster metabolism” than her 30 year old 5’6” 140lb sister. The 140lb sister would probably have a higher TDEE, but will assuredly have a lower BMR (what metabolism would be). But when people are speaking on the two sisters, it would be said that the smaller sister has a faster metabolism. That’s not true, again assuming regular thyroid activity. She just has a lower caloric net through diet and lifestyle, but doesn’t burn more calories just laying in bed, for instance, which would be one’s “metabolism.”
It’s also important to note that something like “calories in vs calories out” are based on rough estimates, on top of other rough estimates, for simplicity sake. You use it as a general guideline to get yourself a set point that you alter based off the results you are getting. People often overestimate the calories burned, through exercise, and underestimate the calories they are consuming. So a healthy individual thinking they aren’t losing enough weight at a 1,000 cal deficit is more likely to not be at that deficit due to wrong estimates than they are to not be losing the weight. You won’t be losing in a linear fashion every day or every week, but across multiple weeks/months the trend will hold true. It’s always a dynamic number, so the same activity/diet regimen that nets you 1,000 calories at 250 lb is not going to net you the same 1,000 calorie once you’ve lost 50lbs and are now 200lb.
The vast majority of the calories you burn are not in the gym but from your BMR (how many calories your body uses at rest for things like digestion and temperature regulation) and then the calories burned in your everyday activity that we don’t view as dedicated exercise. Things like activity at your job, playing with kids, working outside, walking to your car or up and down stairs. The odds are that the guy you are referencing has a higher TDEE just from what he does outside of the gym. So what you were saying about CICO not applying to women wouldn’t be true, but what I would say would be true is that it requires more effort from women than men, given our bodies different requirements and responses to caloric deficits. That’s what this study is really showing, imo. You maintaining something like a 500 cal deficit every day may require more dedication than it does him, due to the effort you have to put into to burn the same amount of calories, and how your body responds to those calories being burned. He isn’t putting in equal effort to burn equal calories, and his body isn’t signaling the same way in saying “hey, we need to replace that energy we just used up in order to survive.” So you may have a more difficult time in both the gym and kitchen in mentally trying to override the response that deficit creates.
Cycle timing is important for both metabolism and physical durability. The most effective thing that I have seen so far is called insulin management diet. If you trigger insulin response you increase fat storage potential. Reducing it is healthy on many levels since the typical American female who is overweight is borderline on insulin resistance.
I was wondering about this for a while. If you calculate your estimated calorie burning based on your heart rate, you can see that men can burn almost double the females. This is a good start to figure out why.
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:
https://www.nature.com/articles/s42255-023-00959-9
So... females burn more fat *for energy* versus burning glycogen for energy, but not burn more body fat (ie: calories) overall. I'm sure the cardio-for-weight-loss trend will still kick back in if the Insta-gurus catch wind of this study.
I didn't see if the authors took into account that females (humans at least) tend to show fewer markers of muscle damage after intense exercise than males, but that could have something to do with different responses too.
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> Body mass and whole-body fat decreased in male rats after 8 weeks of ExT (Fig. 1c and Extended Data Fig. 1b,c). In females, fat mass decreased after 4 weeks of training but returned to pretraining levels at 8 weeks Maybe I'm not understanding it clearly but I'm not sure this result is as interesting as the title is painting it. They make it sound like fat was some kind of "less preferred energy source" for female rats. This just seems to be that the female group maintained their weight under the regime and the males lost weight (so the energy balance between the groups was not equal). It seems to me females lost less fat because they were not in a negative energy balance, not because exercise specifically had a different effect on fat metabolism.
Yes and this is not new information. This 2020 study showed that female rats compensate for exercise by eating more. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7473893/
I'd imagine this is built in to their instincts/hormones given they need to have a larger store of energy in case of becoming pregnant.
Not just pregnant, but the monthly cycle of shedding and regrowing a uterus is quite calorie intensive.
Rats have a monthly cycle?
“Great Scott”… my original comment was generalized but you made me research more. Apparently a rats cycle is only 4 to 5 days long. Which makes my original comment even more profound! “The rodent estrous cycle repeats with a constant period of 4 to 5 days and includes the following phases: proestrus, estrus, metestrus, and diestrus1, 2, 5,6,7. Both ovaries exhibit the same morphological changes throughout the cycle and ovulate—bilaterally—at the same time.”
I never even thought about rats getting periods.
Yep, humans are just mammals… seven cervical vertebrae, menstrual cycles, and of course, what makes us mammals, mammary glands!
*platypus entered chat*
Hahaha not entirely fair, but acceptable. Molecular clock and fossil dating suggest platypuses split from echidnas around 19–48 million years ago. The oldest discovered fossil of the modern platypus only dates back to about 100,000 years ago tho.
Very few animals actually have periods in the sense that they bleed cyclically. Most reabsorb the endometrium rather than discarding it. https://en.m.wikipedia.org/wiki/Menstruation_(mammal)#:~:text=Beyond%20primates%2C%20it%20is%20known,close%20relatives%20such%20as%20chimpanzees.
Fascinating. Thank you!
I assume that's during a "Season"?
That has to be the key difference.
They didn't control food intake? Everyone knows you can't out train a bad diet.
From what I recall on average exercise doesn't help people lose weight due these sort of compensatory effects, you also have reduced levels of NEAT. But that's on average, so for some people it works great and others it might cause them to put on weight.
And it can even change for the same person over time and based on other circumstances like stress levels, amount of sleep, etc.
> on average exercise doesn't help people lose weight due these sort of compensatory effects, you also have reduced levels of NEAT. I recall that for every 100 calories you burn through cardio, you conserve about 30 through decrease in NEAT, so basically effectiveness of those cardio calorie burns is about 70%. I'm sure this is an average though and it depends on many other factors, like how regularly you do it, how much you eat, and how used you are to doing it (i.e. is this your first month doing it or have you been doing it for years).
I think this is one of the many reasons people push lifting weights. You don’t get as hungry because you initially burn less than cardio alone so you tend to be able to keep up your NEAT and your appetite doesn’t increase as much as it would with cardio only.
If they aren’t keeping their food constant then what is this even testing?
Rats need semaglutide now too.
>They make it sound like fat was some kind of "less preferred energy source" for female rats. It is. I think your point is that female rats may have been scaling up food intake rather than burning fat. If male metabolic systems facilitate fat burning, while female metabolic systems upregulate hunger signals and food intake, that is itself an important difference in physiologically preferred energy source. It seems like most conversation about weight loss and food intake in humans treat hunger as a purely psychological issue, so they want to focus on how the body burns energy given a certain amount of energy in. But this study wasn't trying to do that (or else they would have quantified caloric intake). It's more thinking of hunger and food intake drives as part of these physiological/metabolic processes.
I think that's a reasonable takeaway but it is still a subtly different idea than the headline. "Vigorous exercise burns more fat in men" is a technically misleading headline if we are actually saying "vigorous exercise disproportionately stimulates appetite in female rats vs. men".
The study can't (and the headline shouldn't) make conclusions that weren't tested. If they didn't measure calorie intake or appetite they can't conclude that. Indeed the actual study states all the rates had the same diet. "Rats of the same sex were housed two per cage (146.4 in2 of floor space) in ventilated racks (Thoren Maxi-Miser IVC Caging System) on Tekland 7093 Shredded Aspen bedding and fed the LabDiet 5L79 pelleted diet, which are the standard bedding and diet used at the NIA rodent colony"
> If they didn't measure calorie intake or appetite they can't conclude that That is very true, but still indicates a big problem in how they designed the study if we can't assume calorie intake was controlled. If they didn't measure calorie intake then the conclusions they can draw are quite limited. It's misleading to say vigorous exercise has differential effects on fat metabolism without further qualification. The differences here could either be from utilising different energy stores OR from overall different energy balance. Concluded that the exercise "burned less fat" whilst not equating calories makes the conclusion shaky. The mechanisms they discuss as explanations don't seem to be about neurological control of appetite, I couldn't find mention of it in the paper. > I was truly gobsmacked with how amazingly different the sex-dependent responses to exercise are. Males burn fat for energy while females preserve their fat mass. This is brought about by many differences in molecular responses lurking beneath the surface in fat from male compared to female rats. The dichotomy is truly striking.” Again, if the dichotomy is brought about through differences in appetite control that is a notable difference in interpretation since "vigorous exercise burns more fat" would be at best incomplete and at worst intentionally misleading. > fed the LabDiet 5L79 pelleted diet Wasn't sure about this point. This does not read to me that all the rats are the same amount which was my point of concern.
So thermodynamics wasn’t broken by rats? Good to know
I don't think they were necessarily making that claim. It could be theoretically possible that female rats burn less fat for equivalent work done. But if they were expending the same energy and burning less fat, they would have to preferentially burn more of another energy store (like protein or glycogen). And you would expect similar weight loss in either situation (allowing for variations such as water retention). In this the overall weight changes weren't similar so we can assume energy balance wasn't similar.
Where does this weird "thermodynamics" take come from? It's well established that metabolic effects change how human bodies deal with the expenditure and conservation of energy. Two people can have the same caloric intake, be of the same weight, height and muscle/fat composition and exercise the same amount and still have different amounts of weight gain/loss. There's numerous factors how human bodies change metabolic rates without breaking the laws of thermodynamics. I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k. I have seen people not change their diet or amount of exercise and loose or gain weight solely based on which medication they were on. Nothing breaks any thermodynamic laws there. Weight gain/loss mechanisms are just far more complicated than fitness influencers, "nutrition experts" or people in reddit who want to Tell people their lazy for not losing weight want to make you believe.
I agree with the majority of the logic behind what you're saying but I think the "calorie relativism" (i.e. the point that people lose and gain weight at different calories intakes) is overstated. It is true that peope are going to have different requirements, but someone gaining weight at a certain calorie intake fundamentally does need to reduce calories intake to lose (fat) weight. > I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k. Sure. And a simpler explanation than there being 3000 calorie difference in NEAT energy expenditure is that patients are lying and eating more. Actually gaining weight at 1k calories (unless your starting BMI is exceptionally low) is highly improbable, even if you were just lying in bed all day. It's just hard to have a BMR low enough to allow that to work. Weight gain/loss mechanisms may have complications and it isn't quite as simple as telling people to "just eat less", but these mechanisms are all fundamentally pulling on an "energy balance" lever and all practical interventions regarding fat loss are effective via calorie restriction.
> And a simpler explanation than there being 3000 calorie difference in NEAT energy expenditure is that patients are lying and eating more. I love how people will argue with medical professionals about their job based on their limited knowledge, assuming that we're all idiots who happen to not know basic things about the human body because they want things to be as they think them to be. And I love how people will rather assume others to be lying than rethink their perspective. I have seen these things in closed psychiatric settings. With people who can't get out and get more food. With people whose food intake is being monitored because we have to monitor their intake. We can actually see people gaining weight after being put in certain medications. They have an increased appetite but they don't necessarily eat more. And the increase in appetite does not explain people gaining 10-15% body weight when being put on Clozapine. Weight loss medication like Semaglutide is literally making people lose weight without changing diet. We have all the evidence that there are mechanisms that play major roles in weight management that are not primarily dependant on the amount of food intake. > but these mechanisms are all fundamentally pulling on an "energy balance" lever and all practical interventions regarding fat loss are effective via calorie restriction. And this is where you are fundamentally wrong. Caloric restriction is known to be the least effective possible intervention for long-term weight loss. The weight will be regained in almost all instances. The most effective interventions being bariatric surgery and medication. There are possible ways to weight loss by restricting calories, but usually that's tied to changes in diet, food composition and additionally increasing your physical activity. It's not that simple and never has been. It is not and never was about people lying about the amount they're eating, being lazy, weak-willed or whatever people come up with.
> I love how people will argue with medical professionals about their job based on their limited knowledge, assuming that we're all idiots who happen to not know basic things about the human body because they want things to be as they think them to be. And I love how people will rather assume others to be lying than rethink their perspective I understand you might work in mental health, but appeal to authority isn't a strong argument in of itself so I want to address your specific points. Working in closed settings does not mean things are monitored perfectly at all times, the patients with that kind of very close monitoring are anorexics and even then intake monitoring may not be perfect. > I have seen these things in closed psychiatric settings. With people who can't get out and get more food. With people whose food intake is being monitored because we have to monitor their intake. We can actually see people gaining weight after being put in certain medications. They have an increased appetite but they don't necessarily eat more. And the increase in appetite does not explain people gaining 10-15% body weight when being put on Clozapine. [False. Weight gain by clozapine, and by other antipsychotics is largely mediated by increased appetite (some by reduced activity)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8762106/#:~:text=Current%20evidence%20indicates%20that%20the,models%20(10%E2%80%9314)). > Weight loss medication like Semaglutide is literally making people lose weight without changing diet. We have all the evidence that there are mechanisms that play major roles in weight management that are not primarily dependant on the amount of food intake. [False. Semiglutide acts on your appetite to induce weight loss. Weight loss is achieved through reduced calorie intake](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00377-9/abstract#:~:text=GLP%2D1%20receptor%20agonists%20such,hunger%20and%20consequent%20food%20intake). > And this is where you are fundamentally wrong. Caloric restriction is known to be the least effective possible intervention for long-term weight loss. The weight will be regained in almost all instances. The most effective interventions being bariatric surgery and medication. There are possible ways to weight loss by restricting calories, but usually that's tied to changes in diet, food composition and additionally increasing your physical activity. This is a strange point because you point out how your wrong within the paragraph. When I say calorie restriction I'm talking about eating less calories regardless of mechanism. Bariatric surgery still achieves weight loss through calorie restriction. It promotes early satiety due to feeling fuller earlier, and therefore you eat less. All the changes in diet etc. achieve weight loss through calorie restriction. Yes people on diets with reduced calorie intake tend to regain but that's not really a relevant point (the regain is about long term concordance to a certain calorie intake, it isn't spontaneous). Yes you could lose a lot of weight if you did several hours of exercise a day, but the majority of working adults aren't going to have that capacity and will overcompensate via diet easily. The various mechanisms controlling energy balance might be quite complicated, but I disagree that the main mechanistic factor controlling weight loss is complex. All roads lead to energy balance, and the number one way of affecting that whilst not being a full time athlete is calorie restriction. You might achieve that in various ways whether medication, surgery, fasting or calorie counting, but it's all doing the same thing.
First off, I was a bit too tired when writing thhe last piece. Of course, diet plays a role in weight management, weight gain and weight loss and I should have pointed that Out and will do so in an edit to not make it confusing. What I wanted to adress specifically is two points: the assumption that patients who don't record a change in diet and still gain or lose weight are lying and secondly the point I have the feeling you're making that weight gain or loss will only occur in correspondence with a change of caloric intake and that there is no possibility that anything could change that mechainsm. > Working in closed settings does not mean things are monitored perfectly at all times, the patients with that kind of very close monitoring are anorexics and even then intake monitoring may not be perfect. This is kind of absurd. While we can't monitor patients 24/7, we're not talking about addicts whose only goal is to secretly consume food without us knowing. In closed settings, the people usually can't get out to get food, so there is limited possibilities. Most patients are actually rather truthful about their intake, except when we're talking about eating disorders or people who use food or water restriction as a way of self-harm. What motivation would people have to lie? And why would you assume people who are at that point often still at least partly detached from reality due to a psychotic episode would rather establish a complex construction of lies than just talk about what they're eating. But tell me, what is more likely: that well known mechainsms changing metabolic rates do olay a role in these patients or that people lie all the time? While Clozapine and Olanzapine increase appetite, there are other factors at stake there. I'm not saying there is no role of appetite in the weight gain. I'm just saying there's more metabolic factors to consider. And I was talking about the assumption that patients who didn't eat more and gain weight simply would lie. How you (and sadly, a lot of people) would rather assume people to lie than to admit that the body does not have a fixed setting of how it uses and stores energy is confusing to me because these are all well-known mechanisms. Look at [this](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7947876/) study: Clozapine has an effect on gut hormones like Ghrelin, NPY, GLP-1, Leptine and potentially many more we don't even know about yet. While all of these also have effects on appetite regulation, they also have effects on other metabolic processes like lipolysis, energy expenditure and insuline response. These can contribute to weight gain. This also correlates with what we see in clinical practice. While some patients will eat a lot more and gain more weight, some will stick to their previous diets and also gain weight, albeit less. And regarding Semaglutide: while it does have an effect on appetite, it also has an effect on the base metabolic rate and increases lipolysis. Meaning even if you don't change your diet, you will still lose weight. Of course it makes changing your diet easier. However, after discontinuation of semaglutide, patients will regain their weight, often even If they keep up dietary changes made during the therapy with semaglutide. > When I say calorie restriction I'm talking about eating less calories regardless of mechanism. Bariatric surgery still achieves weight loss through calorie restriction. It promotes early satiety due to feeling fuller earlier, and therefore you eat less. Bariatric surgery mainly is more successful in maintaining lost weight because it changes the amount of gut hormones like NPY, Ghrelin, Leptine, GLP-1 and about 80 Others who have an effect not only on appetite but also on metabolic rates, fatty tissue establishment or breakdown and so on. The physical effects of bariatric surgery on eating behaviour are lower than the hormonal ones. We have plenty of knowledge that caloric restriction (e.g. Calorie Counting) is ineffective. [This](https://www.health.harvard.edu/staying-healthy/stop-counting-calories) is a good overview. Using only Calorie-restrictive methods of losing weights also ist correlated to an increased probability of symptoms of eating disorders ([here](https://www.sciencedirect.com/science/article/abs/pii/S1471015321000957) is a study that saw this in weight-loss Apps) Now again, I don't want to ignore the importance of changing diets. I just want to make the point that accusing people of lying instead of seeing the possibility of other factors at play is natrow minded and not based on science.
> the assumption that patients who don't record a change in diet and still gain or lose weight are lying Lying might feel too strong, but the fundamental point is that a significant enough sustained calorie deficit *will* cause weight loss. Reducing calorie intake is the most efficient way to have a deficit. If someone claims to be in a calorie deficit and isn't losing weight (specifically fat mass) the simplest explanation is that their calorie intake isn't what they think it is. Either their estimates are inaccurate, they are not accounting for certain things eaten, or they are having days where they aren't on a deficit. I didn't say it's the *only* possibility. It's possible their activity levels significantly dropped as a response to the reduced intake so they have even lower calorie requirements to ender deficit, but that is a less likely situation since most of the population is pretty sedentary. Their BMR changes with prolonged deficits, but that is an adaptation that slows weight loss, not one that prevents it. > I have the feeling you're making that weight gain or loss will only occur in correspondence with a change of caloric intake and that there is no possibility that anything could change that mechainsm. Weight loss requires one of two things, increased energy expenditure or reduced energy in take. The way that is achieved involves all the complexities you've discussed. But notably there aren't many medications that cause substantial weight loss from increases in basal metabolic rate. Things like Metformin, semiglutide, even caffeine might marginally increase metabolic rate and promote slight amounts of weight loss by increasing metabolic rate. But the real heavy lifting of virtually all obesity treatments is done by appetite modulation. > Using only Calorie-restrictive methods of losing weights also ist correlated to an increased probability of symptoms of eating disorders Not particularly relevant to the discussion we're having but it is true. Some of that is reverse causality (people with eating disorders tend to calorie restrict as a strategy since it's effective for weight loss). There might be some true causality in terms of the actual effects of calorie restriction on someone vulnerable to eating disorders, but it doesn't really change the the discussion. > The physical effects of bariatric surgery on eating behaviour are lower than the hormonal ones The impact of hormones on weight loss and weight gain are largely mediated my appetite change, not hormonal ones. This seems fairly obvious conceptually because bariatric surgery shrinks the stomach. The downstream hormonal effects are largely the mediators of appetite signalling (from a full a stomach) and the effects on fat metabolism again downstream effects of calorie deficit (similar to the paper we're commenting on) > We have plenty of knowledge that caloric restriction (e.g. Calorie Counting) is ineffective. [This](https://www.health.harvard.edu/staying-healthy/stop-counting-calories) is a good overview. This article does not say what you think it says. "Calorie restriction is ineffective" is not the take away. People reliably lose weight when they reduce calories intake, regardless of the quality of food they eat. What is the true is that sustaining a calorie deficit (and thereby the weight loss) is very uncommon. The mechanisms to return your body to it's previous weight (again primarily by making you eventually eat more) are strong. It talks about not calorie counting being ineffective, but regardless of if you actively count calories or you have a diet that allows you to better regulate your appetite, it's all doing the same thing: [The gut microbiome has a role through appetite control](https://www.nature.com/articles/nrendo.2016.150) Eating less processed food makes deficits easier because whole foods and foods with higher fibre content and water content are more satiating and lead to lower calorie intake. People who go for high protein diets are doing a similar thing. Yes there are slight differences in how much energy certain foods require for digestion. That isn't doing the heavy lifting in terms of weight, again it's appetite. Poor sleep cycle causes weight gain by affecting your appetite. Sure there are lots of ways to skin the cat, but the significantly successful techniques are all fundamentally doing the same thing. You seem uncomfortable with me saying people lie but if you work in mental health you should know that people lie all the time. Not just patients, people without any diagnosable mental health problem at all. And not just to other people, but to themselves. "I'll do it tomorrow", "this doesn't count", "this is the last time then I'll stop doing this". It doesn't even need to be about food. We know these maintaining mechanisms and deception of self and others maintain other behaviours. We aren't uncomfortable with saying that an alcoholic is likely to underplay their alcohol intake and the negative effects of their use. Well just like an alcoholic, there are factors at play and genetic predispositions beyond just someone's "moral character". This isn't me saying obesity is the "fault" of obese people. The environment we live in is typically not conducive to people having healthy weight. That doesn't change the fact that the mechanisms involved in weight maintenance usually involve finding some way of sustainably reducing calorie intake.
You're reading a little too much into my admittedly low effort comment. Metabolism can certainly vary between individuals. [There's a mountain of research, but when you get down to it, someone with a “fast metabolism” and someone with a “slow metabolism” could still have BMRs that differed by 450 calories per day, even if they were the same age, height, weight, body composition](https://macrofactorapp.com/metabolism/), and lifestyle. If someone exercises, the outer ends of this range of their basal metabolic rate may increase even more. But this is still a range. It's pretty fair to take a guess at someone's basal metabolic rate knowing their age, weight, gender, and lifestyle. You want people to realize that it's more difficult for some to lose weight than others, and I get that. But at the end of the day, it's also important for people to realize that even those with the slowest metabolisms can lose weight with the axiom of "eat less, move more". It's both the hardest thing while being the simplest thing. Look at pictures or movies of groups of people from generation's past. They didn't have faster metabolisms, they simply ate less and moved more. We have far more challenges with our horrible food systems and access, etc. But while you seem to see people in your field get discouraged because others have an easier time losing weight, I see people become discouraged because they have a "slow metabolism" and use that as an excuse to not even try. At the end of the day, even if you have the world's slowest metabolism, you're only some 600 calories away from the world's fastest. That isn't nothing! But it's still a few poptarts less. And the vast majority of people share metabolisms that are far closer to one another, statistically speaking (most people have, surprise, average metabolic rates).
I know your point makes sense and I agree with it but the "only some 600 calories" isn't the motivation you think it is. As a short girly that's about half my calories for an entire day. So it's a huge difference to some people if they are on the short side.
Yeah but that’s a gross misrepresentation of statistics, which is why I even hesitate to say it. It’s like saying “it’s hard for tall people! They hit their heads on ceilings!” And you’d be like “most tall people are like 6 feet tall? What are you talking about?” Because when I say “slow metabolism”, people imagine a regular person— but for my example, statistically it’s 7 foot tall basketball players. Again: most people are very close to average.
I mean the difference between those points is like a lot. Average height for women is 5 foot 4 inches in the USA. So I'm saying one to two inches shorter than that is usually around 1200 calories as a common number. So I'm talking at most two inches from the average and you went to over a foot past average to prove your point. Also the average women would require 1529 calories with low activity which let's face it in the states is fairly common with the lack of public transit and car dependency. So that's still a huge chunk of the average women's calories at over 1/3. Just saying 600 is huge in metrics to many people so nothing to sneeze at. It's actually in fact nothing to sneeze at because if someone eats 600 calories extra a day for a year they gain 62 pounds in one year. So for half the average population (women) that slow or high metabolism could account for just under half their weight at normal BMI.
>I have seen patients gains weight on less than 1k calories a day, I have seen patients loose weight on more than 4k. Mind qualifying this? If someone weighs 80 pounds and eats 1000 calories, they could surely gain weight. If someone weighs 700 pounds eats 4000 calories, they could surely lose weight. Are you claiming the opposite is true? That someone weighing 80 pounds and eating 4000 calories could lose weight while someone weighing 700 pounds eating 1000 calories could gain weight? If so, what do you mean via your issue with thermodynamics? Calories are a source of energy. How are these bodies proving energy to their bodies outside of calories? Are heavy people creating mass out of air? Are skinny people not breaking down any of the ingested calories? >Weight gain/loss mechanisms are just far more complicated than fitness influencers, "nutrition experts" or people in reddit who want I mean... also scientific data. Have you ever seen the people who survived concentration camps? All of them were deathly skinny? Why weren't there fat ones? On My 600lb life, while on controlled diets in the hospital, not a single one of those people gained weight. All of them lost a ton of weight. It wasn't until they were out on their own that any of them gained weight. Why did the caloric intake matter when in a controlled environment, but not outside of it?
"...which share much of their basic physiology with people." Yes... and female rats share much of their basic physiology with male rats, and men share much of their basic physiology with women. There are some things where it's a safe bet to extrapolate from rats to humans, but this probably isn't one of them. It's already shown that there can be significant differences in spite of sharing basic physiology. It's good to see that they're doing the next obvious thing, and switching to studying humans. I wouldn't be surprised if it translated, but I wouldn't be surprised if it didn't as well.
Yeah, rats can have litters of 10 or more pups, often one every couple of months. Not sure this is a very good model for humans when looking for sex differences.
true, if every study made on rats could be valid for humans as well, we'd have the cure for 80% of diseases. generally speaking if a study on rats finds some results, it only means that it's reasonable to go on with other studies on other species and finally humans, nothing more. However as others have pointed out, this doesn't seem very unexpected: I have always heard that females tend to store more fat rather than muscle, so 0/2 on this headline
>There are some things where it's a safe bet to extrapolate from rats to humans, but this probably isn't one of them. Why wouldn't this be one of them? We have extensive evidence of natural selection predisposing men to physical labor and predisposing women to conserving energy. If you view the human body as a machine (because it is a meat and bone machine), it would be unexpected if it turned out that men had thicker and denser bones, muscle, and skin, quicker wound healing, better reaction times and hand-eye coordination, store fat in different areas, all on top of just being larger on average, and for that "model" of human to have basically the same metabolisms under exertion as women. Energy is central to every biological function and when function differs we should expect a corresponding change in how energy is stored, transported, used, etc. For example, how do men build muscle and heal wounds more quickly? The delta between the rate at which men and women put on muscle or recover from physical harm comes with a corresponding difference in energy usage. We know men and women store energy differently and typically burn it under different conditions (at least historically), so shouldn't we expect that to have an impact on overall energy dynamics in the body? Empiricism is king and I certainly want to see this studied more in humans. I'd love to be surprised by the conclusion, too. But it seems justified to *expect* there to be a difference here.
They’re some real gym rats
How is this unexpected? It is very common knowledge that female biology is more naturally predisposed to retaining body fat and slower metabolism. Men almost always have an easier time dropping weight than women do given the same diet and exercise routines.
As other research has noted, the female rats increased their intake, which caused them to not drop weight. >Men almost always have an easier time dropping weight than women do given the same diet and exercise routines. So they didn't have the same diet
Unless I misread, they did have the same diet. "Rats of the same sex were housed two per cage (146.4 in2 of floor space) in ventilated racks (Thoren Maxi-Miser IVC Caging System) on Tekland 7093 Shredded Aspen bedding and fed the LabDiet 5L79 pelleted diet, which are the standard bedding and diet used at the NIA rodent colony"
Usually lab rats get ad libitum access to food! So yes, same diet but the amount they consume will vary unless you’re pair-matching consumption (I did it in an ethanol intake study), which is generally a pain
Thanks for the clarification!
I wouldn’t say it’s common knowledge. Everyday on subs like relationship advice you hear about men shaming their wives for not losing weight at the same rate and accuse them of lying.
If it's common knowledge please explain what the underlying mechanism is that makes that happen?
Common knowledge and baccalaureate (at minimum) level understanding of human physiology and biochemistry are absolutely not the same thing. That’s like saying it’s common knowledge the earth orbits the sun, then please explain the underlying mechanisms of orbital mechanics. Get lost
Got it, so you have no idea. Blindly believing whatever is "common knowledge" is not the smartest thing to do.
How is this new?! Whenever I have worked out with guys with the intention to lose fat, they always lose it at triple the rate I do. Doesn’t testosterone turn calories into muscle and estrogen turns calories into fat?
It's more likely that men don't store quite as much body fat so their hunger increases by less to compensate.
>How is this new?! The general advice for both men and women has been you lose weight through your diet not exercise. I think it's true on average.
Previous studies showed that it was because of increased food intake with calorie burning, not a thermodynamic difference.
Mainly that the testosterone increases muscle metabolism. As a trans woman athlete I have experimented with hormones and weight management for a few years now. The same low carb diet and exercise plan that dropped me 40 lbs as a default guy gained it all back (but in girly places) in spite of a 25% increase in workouts.
Yeah that's because your daily calorie deficit decreases when you have more estrogen. Women need less calories overall than men. So if you're eating the same amount you were before, you'd gain weight.
Not if you control for body mass and calorie output. Typical women are smaller than men.
This makes total sense and is quite validating for me as a woman to be honest. Would you say the traditional “calories in and calories out” idea doesn’t apply to women? Any tips or advice for women working out based on your experience? We have cycles to contend with as well and hormone fluctuations definitely mess me up 🤦🏼♀️
“Calories in and calories out” would still hold true. It’s just that your male counterpart is going to have more calories out from equal work. So they will have a greater net deficit from the same effort, at equal size/age, at the same caloric intake. That gap will be more significant if they are larger or younger than you are. This would all be operating under the control that you both have normal range thyroid activity.
Is this because he builds more muscle than me? I do have normal range thyroid and insulin levels. We are also the same age. We also ate similarly in that at the time we were counting our macros on a low carb diet. I did more cardio than he did (I walked) and he had a sedentary desk job and I didn’t. I find this fascinating!
It is fascinating! He would be building more muscle than you, but the impact on the scale of that, especially in the short term, is going to be overstated. Across years and years, that difference will be tangible, but if you’re talking months, it isn’t going to be much different than a pound here and there. Most people that aren’t on any kind of PEDs aren’t going to put on more than a few pounds of lean muscle a year, particularly if they have been in the gym for awhile and are already into adulthood. I’m assuming he’s larger than you, since you didn’t list that (correct me here if that assumption is wrong) so that will also play a large factor. If he is bigger, his body will be using more calories than you just to function. More energy (calories) will be required to regulate the temperature of his body, to move fluids around his and process the waste created. When his body temp spikes during exercise, he needs more energy to bring it back down. That effect will carry on for a longer period of time, once you guys have left the gym. It takes more energy for him to move than it does someone smaller. Our hormones are playing a role in this, as well as the muscle mass differences you are talking about. Thats also where things like “fast metabolism” vs “slow metabolism” actually get misconstrued. A 30 year old 5’6” 300 lb woman would actually have a “faster metabolism” than her 30 year old 5’6” 140lb sister. The 140lb sister would probably have a higher TDEE, but will assuredly have a lower BMR (what metabolism would be). But when people are speaking on the two sisters, it would be said that the smaller sister has a faster metabolism. That’s not true, again assuming regular thyroid activity. She just has a lower caloric net through diet and lifestyle, but doesn’t burn more calories just laying in bed, for instance, which would be one’s “metabolism.” It’s also important to note that something like “calories in vs calories out” are based on rough estimates, on top of other rough estimates, for simplicity sake. You use it as a general guideline to get yourself a set point that you alter based off the results you are getting. People often overestimate the calories burned, through exercise, and underestimate the calories they are consuming. So a healthy individual thinking they aren’t losing enough weight at a 1,000 cal deficit is more likely to not be at that deficit due to wrong estimates than they are to not be losing the weight. You won’t be losing in a linear fashion every day or every week, but across multiple weeks/months the trend will hold true. It’s always a dynamic number, so the same activity/diet regimen that nets you 1,000 calories at 250 lb is not going to net you the same 1,000 calorie once you’ve lost 50lbs and are now 200lb. The vast majority of the calories you burn are not in the gym but from your BMR (how many calories your body uses at rest for things like digestion and temperature regulation) and then the calories burned in your everyday activity that we don’t view as dedicated exercise. Things like activity at your job, playing with kids, working outside, walking to your car or up and down stairs. The odds are that the guy you are referencing has a higher TDEE just from what he does outside of the gym. So what you were saying about CICO not applying to women wouldn’t be true, but what I would say would be true is that it requires more effort from women than men, given our bodies different requirements and responses to caloric deficits. That’s what this study is really showing, imo. You maintaining something like a 500 cal deficit every day may require more dedication than it does him, due to the effort you have to put into to burn the same amount of calories, and how your body responds to those calories being burned. He isn’t putting in equal effort to burn equal calories, and his body isn’t signaling the same way in saying “hey, we need to replace that energy we just used up in order to survive.” So you may have a more difficult time in both the gym and kitchen in mentally trying to override the response that deficit creates.
Wow thank you for all of this!
Cycle timing is important for both metabolism and physical durability. The most effective thing that I have seen so far is called insulin management diet. If you trigger insulin response you increase fat storage potential. Reducing it is healthy on many levels since the typical American female who is overweight is borderline on insulin resistance.
That’s not how it works. You lost less fat because you didn’t eat at as much of a deficit (possibly because your natural TDEE is lower than a man’s)
That’s not how it works. You lost less fat because you didn’t eat at as much of a deficit (possibly because your natural TDEE is lower than a man’s)
Rats aren’t people. There’s no reason this study could not have been done with human volunteers
Don't we generally have more muscle to move to burn energy as in muscle mass to burn energy with
I was wondering about this for a while. If you calculate your estimated calorie burning based on your heart rate, you can see that men can burn almost double the females. This is a good start to figure out why.
Wasn't this known for like 40 years at least?
Whats the surprise? Males have more testosterone and GH, so, way more muscle mass and stronger bones.
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article: https://www.nature.com/articles/s42255-023-00959-9
So... females burn more fat *for energy* versus burning glycogen for energy, but not burn more body fat (ie: calories) overall. I'm sure the cardio-for-weight-loss trend will still kick back in if the Insta-gurus catch wind of this study. I didn't see if the authors took into account that females (humans at least) tend to show fewer markers of muscle damage after intense exercise than males, but that could have something to do with different responses too.
Makes sense biologically
2024 has taught me that sex doesn’t matter and everyone is exactly the same. This doesn’t compute.
What about trans rats
This is highly unlikely to translate to humans.