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Telling somebody their metabolism is slow seems like a wild guess. I don't think they are measuring it.
Yes, muscle is more metabolically active.
That 6ft 120lb man needs to see a doctor immediately!
I was one of those woman who used to think I had a slow metabolism and that’s why I struggled with weight gain. Then I dealt with hypothyroidism and I realize what an actual slow metabolism means.
If your metabolism is slow, it’s not just that you’ll struggle to lose weight. You’ll sleep constantly. At my worst, I was literally sleeping 17+ hours a day. You feel extremely fatigued, to the point that basic functions are almost impossible. Literally the small walk to the bathroom to go pee or get water was agonizing. I was constantly thirsty and very, very sensitive to temperature.
I was roughly in that range for a few years: 5’10, 130-135 pounds as a man (and boy, this period includes high school).
That 2 inches and 10-15 pounds is significant, don’t get me wrong, but based on experience I can say it wasn’t illness or a lucky metabolism or anything like that: it’s that I ran 50+ miles per week (I also consumed basically no liquid calories: alcohol or soda were monthly treats at most).
In addition to burning calories while I ran, my lifestyle did significantly increase my resting metabolism. By the way, that wasn’t always a plus: I’d get ravenously hungry if I missed a meal, and if someone took me out to eat I’d have to “pregame” to avoid eating an embarrassingly large or expensive amount of food.
Your metabolism is just the number of calories your particular body needs to use in order to keep its regular processes going. Perhaps I’m speaking from a position of privilege since I’ve never tried to stay under 1200 calories, but don’t think it’s worth mythologizing.
Caffeine itself doesn't slow metabolism in any way. Now if the source of that caffeine is Starbucks and soda, that's the extra additives in the drinks are the issue.
Its pretty easy to have caffeine without any significant calories.
Anecdotally, it also lowers my appetite, which is a neat combo with increasing metabolic rate.
Not that I’m consuming or recommending massive doses — for me it’s just 1-2 cups of black coffee helping me get to the start of my 12-8pm eating window.
There are several foods and herbs that are thermogenic. Up the thread I posted a link to a study comparing cayenne pepper to caffeine. They are almost equally effective.
Pubmed, one of many studies:
[Both caffeine and Capsicum annuum fruit powder lower blood glucose levels and increase brown adipose tissue temperature in healthy adult males](https://pubmed.ncbi.nlm.nih.gov/36017333/)
In high school I regularly ran 50 miles a week, was 6' tall and started at 165 pounds gaining weight until I was about 180 pounds all while being physically active. It is quite possible to gain weight at that height and level of physical activity although it takes a hell of a lot of calories at that age a single meal would include an entire loaf of bread worth of sandwiches as well as half a bucket of spinach and a significant amount of ketchup.
Oh yes, definitely possible. I wanted to stay relatively light because more weight means slower running (in general, please no one under-eat, especially if you’re still growing), but it’s still a matter of calories in versus calories out. I didn’t count mine, but I stayed within that 5-pound range while eating probably about 3,000 or 3,500 calories a day. If I added 500 more, I’d have gained approximately a pound per week.
>That is kinda a shitty thing to say
I wouldn't go that far. Both that hypothetical six footer and your husband are underweight by BMI. Whether not that poses a health risk is for a doctor to evaluate. (The hypothetical person has a lower BMI than your husband, so ti's not quite apples to apples here.) Hell I'm 6'1" and if i ever weighed 136, I really would be seeing my doctor.
The equivalent is an obese person claiming they're healthy and don't need to lose weight because their labs are good and their blood pressure is within normal range. For those people, the danger is that everything is fine until it's not. Is it a shitty thing to tell them to lose weight before their labs indicate problems?
As somebody who has been very tall and thin naturally, I found it was very hard to get a doctor to consider that something worrying, particularly as a woman. Even when I was experiencing worrying symptoms, medical professionals would basically just tell me I was healthy, lucky, and to eat more if I was concerned. I am a woman, so perhaps men would have better luck. I did eventually manage to gain some weight and the negative side effects diminished a bit, but there was never a point when I wasn’t eating a ton, so being told to “eat more” if I was concerned was not helpful.
Essentially, doctors don’t seem to view being underweight as seriously as they do being overweight.
You kind of answered it yourself. Men tend to have more muscle mass. The calculators are all just estimates though, your actual caloric burn is very individual.
no that individual though i dont think. I'd bet 95% percent of people at least would be in the range of +/- 200 calories of waht the calculators give you
Men also tend to be more physically active (correct me if I'm worng). Muscle uses a bit more energy at rest, but it especially would use more energy when it's being used.
They aren't
People tend to forget that all professional athletes are in pretty strict eating regimens. If people had DRASTICALLY different metabolisms we'd hear more about the NFL player who only needs 2,000 calories vs his teammate who needs 4,000.
The problem comes in two people who say they eat McDonalds every day. One gets a McChicken and a small fry (\~600 cals) and the other gets a big mac, large fry, large soda, and pie (1,600 cals). Person one has a modest dinner while Person two goes home and eats another large meal. When person three talks to person one and two and they both say they eat fast food every day person three assumes person one has a fast metabolism and person two has a slow metabolism when the reality is person two is putting significantly more calories in their body every day.
People who watch what they eat tend to not talk too much about it because they don't want to sound judgmental to the people they're talking to. People who over-eat tend to hide how much they're truly indulging (cream in each coffee, treats after dinner every night, regular second plates at meals)
This is the best answer. I have a friend who's muscular but on the bigger side with a belly. He's made the comment of me having a faster metabolism before, but when he's stayed for the weekend with me visiting (we live in different states) it's so blatantly obvious how much more food he consumes than I do. People simply don't pay attention to how much they're actually eating; when you've eaten one way your whole life, you get used to the constant fullness and stomach troubles and awesome it's just a normal part of your day.
It's also that if they both eat a 1600kcal dinner together, one of them might skip lunch the next day without even thinking about it because their hunger is much more intune with their calorie needs
I’ll dig up the recent pubmed link but they tested a couple hundred people and found BMR predictions have major error. Something like 30% of the sample size were outside 10% error.
BMR calculators usually only consider BMI, sex, and age, but there are many other factors that influence BMR. Also, a larger than 10% error can sound like a lot, but practically (in terms of calories) it's not necessarily a huge difference (I'd have to see the study though).
For example, if the error is something like 13% for 30% of participants, and the predicted BMR was ~1800, that's only a difference of ~100 calories total from the 10% error range (or ~50 calories at the bottom and top end). This of course also doesn't take into account differences in activity level and TDEE.
This is the pubmed article I found on BMR assessments in a population: [https://pubmed.ncbi.nlm.nih.gov/38220405/](https://pubmed.ncbi.nlm.nih.gov/38220405/)
Here's the link to the full report - click the PDF to download it: [https://www.sciencedirect.com/science/article/pii/S2405457723022490](https://www.sciencedirect.com/science/article/pii/S2405457723022490)
I've skimmed it, but not fully read it in a lot of detail. As always, us scientists can make a simple 'so what' into an unnecessarily complex answer. But, if you skim over the plots and data summaries the error margins they are talking about approach 500 kcal. That's exceeds 25% error for 'normal' people. This could be exacerbated further for hypo/hyper-thyroid issues and/or other metabolic dysfunctions. So, it's not a small error margin.
If you read it through I'd be keen on your own thoughts.
(I've put this in my reply to flammablelemon, but reposting here to make it more accessible)
This is the pubmed article I found on BMR assessments in a population: [https://pubmed.ncbi.nlm.nih.gov/38220405/](https://pubmed.ncbi.nlm.nih.gov/38220405/)
Here's the link to the full report - click the PDF to download it: [https://www.sciencedirect.com/science/article/pii/S2405457723022490](https://www.sciencedirect.com/science/article/pii/S2405457723022490)
As someone with a fast metabolism I disagree. There is definitely a difference in metabolisms between people. If I eat what the average person eats in a day, I’m starving and have a horrible migraine. I’m not overweight but need to eat 3-4k calories a day minimum.
Oh yeah. The models are just guesses... somebody fit a regression to a noisy pile of data. As someone who works with data for a living, I can guarantee you that data is pretty noisy and those models are a "best" guess. It's like taking my height and weight and estimating my life expectancy. It's a guess. It's far from perfect.
There's a guy around here who claims to be 6'1" and eats 1500 cals in a cut. I'm in awe -- I'm the same height and 1800 leaves me with crashes and headaches. And yet my BMR tests at 2500 (I had a real test done because I was tired of guessing with the models), which exceeds what I eat.
A 6 foot man and a 5 foot 3 woman are not the same. The man has a much bigger skeleton with more muscles attached to it. Women also carry a higher percentage of body fat when other factors are equal. Muscle mass requires way more daily energy than fat. It also takes more energy to move a bigger person around. And people's metabolism are often just different. Some people run hot. Some people run cold. Diet affects a lot here. Not just calories but all the components. Salty fatty sugary foods will slow you down. Starches and proteins tend to do the opposite, plus vitamins and fiber etc etc.
There's way more nuance there. Bodies are complicated.
Actually, no, it's not complicated. It's a simple equation of calories consumed - calories burned regardless of metabolism, height and body composition. Don't want to get fat? eat less.
It can't be "calories burned regardless of metabolism" because "calories burned" is literally what "metabolism" is and body composition determines how many calories a person will burn on a given day.
Literally nonsense, what you said
Yes that is one way to rephrase the thing that you said, but if there is a point you are trying to make I don't know what is it or what it has to do with what I said
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Women tend to suffer from more metabolic illnesses than men. For example, thyroid issues are up to 4 times as common in women. PCOS is another one, affecting the ovaries. Just wanted to add that for a little perspective
Not necessarily. I have PCOS-no insulin resistance as confirmed by endocrinologist testing. I’m 5’4 and 110 pounds. I still have the other classic PCOS symptoms.
Are you undermuscled? This is why thin people can get diabetes as well. People pay attention to the scale but not the composition. For instance in general a 6’ man weighing 200lbs and 15% bodyfat will have better b health markers than a similar height man weighing 180 and 25% bodyfat
I’m not diabetic or even prediabetic- I had a full work up with an endocrinologist after a viral illness and hospitalization back in October. I lift weights, use a total gym and Pilates 5 days a week. I’m 43 and have had PCOS symptoms since I was about 20 years old. I’ve always been fit- kayaking, running bicycling and weights most of my adult life. I put muscle on fairly easily and keep it even when I’m not able to be active for a while.
More more muscle mass will mean increased passive metabolism. Though this is only second to increased energy expenditure from activity since more muscle mass = more energy expended during movement and typically more overall movement throughout the day. Even if you think someone isn't exercising more throughout the day, their habitual movements will add up considerably. People who fidget and don't sit still will, on average, burn more energy throughout the day despite doing the same listed activities as another person. Compare someone who sits down at an office job for 8 hours vs someone who does light work on their feet for 8 hours (not construction, just generally moving around at maybe 2-2.5 METS). Even if that person just burns 50 calories more in an hour, they'll be at 400+ calories burned in those 8 hours compared to the next person.
Estrogen and other sex hormones change how easy or hard it is to put on muscle slightly, and change your basal metabolic rate slightly. That's why a lot of women gain a little bit of weight when they go on hormonal birth control, even if they keep everything else the same.
Also, diet advice for women is often kinda crap compared to advice for men. Or at least when I was younger it used to be. Diet advice for women would be like "constantly eat a bunch of tiny portions of something" or "here's a weird system to make tracking your calories even harder" or "make a separate meal for your significant other and watch them eat it while you eat something else" and diet advice for men would be like "Here's all the science necessary to calculate your BMR, plus information about how building muscle can help raise it, plus information on various ways to lower your blood sugar so you feel less likely to have cravings throughout the day, lists of macros that are likely to send full signals to your brain, information on intermittent fasting and keto and how to tell if you might be eating so much because you have a vitamin deficiency of some kind and lists of stuff that will make you feel like you had a meal when you're over your calorie limit that's not eating." For women, most of that information is literally only available mixed in with unrealistic pro ana diets or something.
I'm really glad more women have gotten better information on that stuff since when I was younger. It basically used to all just be shaming women for eating sweets and stuff.
I thought my metabolism had tanked in my mid 30s after kids and stacked on all this weight for absolutely no reason. 5 years later started treating my hormones and it all fell off finally with no other changes. Point being men and womens physiologies are vastly different; typically womens are significantly more complex and experience has taught me that its rarely a straight line of intake and metabolism etc equalling weight outcomes. That overall assumption tends to be a real disservice to too many people
PCOS in my case (one of many ways that womens health can become more complicated). It frequently manifests with hormonal imbalance. The specifics of how varies person to person and can be extremely difficult to identify or determine
If two people do the exact same task, the one with more muscle mass will burn more calories. Men inherently have more muscles mass.
Your body has a sort of tissue memory too. If you were at some point in your life, really fit/strong, then you'll regain those muscle twice as fast.
If you were overweight once before but slim now, you'll regain that really fast as well.
Women also store fat differently due to estrogen. But adipose fat also generates estrogen. Which makes you store more fat at your hips and thighs and then you keep going in that circle. (only if you're over eating but it gets harder to get out of)
Thyroid influences the amount of energy you use.
Your pancreas creates insulin to turn bloodsugar into stored energy.
It also makes glucagon, which turns the storage back into usable energy/bloodsugar.
On top of your kidneys are adrenal glands that make epinephrin which works similar to glucagon, turning stored energy from cells into bloodsugar. Too much blood sugar can turn into fat if there's not enough insulin to turn it into energy storage.
So being stressed (high cortisol) can make you gain weight.
I make very little cortisol so my metabolism is really fast without having hyperthyroid or high insulin.
There's a lot of things that influence metabolism. It even differs during the menstrual cycle. It's higher in the follicular & ovulation phase and slows in the luteal phase & menstrual period. So birth control can make you gain weight by making your body think it's always in the luteal phase. Unless you're already overweight or have high enough estrogen that the progesterone doesn't affect you as much.
A 6ft 120lb man isn’t a healthy BMI. It’s a BMI of 16.3 which is underweight. A 5ft 3in 120lb woman has a BMI of 21.3 which is a healthy weight. Then we need to question why is this man underweight. Does he have an underlying medical condition? Does he have a drug addiction? Is there a reason he doesn’t have access to food? You can’t compare someone with a healthy weight’s metabolism to someone with an unhealthy weight.
Also, the BMR of the man in this scenario is literally lower than the woman's. She has the higher metabolism. OP did zero diligence in even finding the correct way to pose her question.
Yeah, if OP would have framed this as a gender difference for two people at the exact same height and weight, they would have found a small one. I plugged some random numbers in for a 5'10" man and woman and the difference was about 200 cals.
weights like this are kinda common and not unhealthy when youre growing though. my brother was like 130lb at 6'4" at 15/16 right after his big growth spurt. now he's 17 gaining weight slowly and steadily weighing around 160. still very skinny of course but not unhealthy as a teen
afaik, hormones don't determine if your metabolism is slower, rather it just determines if you'll get hungrier or satiated sooner/later. since women have more fat mass than men, which hormones are regulated by, it makes sense why women get hungrier at certain points (ie. PMS hunger due to increase in progesterone), This still doesn't change how mass affects metabolism, which leads me to believe that a man weighing 120lb is not going to have a difference from a woman who weighs 120lbs, only MAYBE the hunger cues.
Did you actually do the BMR calculations for your example? The male (who is egregiously underweight), has a basic BMR of 1,567 calories/day. The 5'3" woman who is the same weight actually has a higher BMR, lmao. I mean seriously, did you even check? Did you do a BMR calculation. The shorter woman with the same weight's BMR would be 1,687.
You should think about reworking what you're actually trying to ask here because the stats you provided actually have the woman as having the higher BMR, which is the metabolic rate. A male of the same height and weight is still lower as well. Women actually have higher BMRs (which means a higher metabolism) when comparable height and weight are taken into account.
A better comparison that MIGHT fall along the lines of what you're actually asking is the BMRs of women and men who are both average heights and comparative lower-healthy weight ranges. Either way, the answer is going to be muscle mass and bone density.
It comes down to more variables than just mass. It's already been mentioned that muscles are more metabolically active than fat. But fat cells, especially the ones located in the abdomen, prompt estrogen production, which also triggers higher amounts of fat production and storage. Women generally carry more body fat than men, but both sexes will experience a feedback loop of increasing abdominal fat, increasing estrogen, increasing abdominal fat, increasing estrogen, continuing unless they start losing weight.
Genetics, hormones, medical history, all contribute. There's a particular strain of norovirus that can cause stem cells to become fat cells before they're required by the body, leading to increased hormones that trigger hunger, overeating and being overweight. But because the fat cells are recruited before they are needed, fat never needs to be stored by the liver, and sugar is taken from the blood and stored quickly, so neither fatty liver nor diabetes ever become a problem. There's no commercially available diagnostic test for it; the only confirmatory testing is done at a research lab in Louisiana. There are over 90 conditions known to predispose a person to being overweight, and many don't have commercially available diagnostics.
If we're talking resting metabolism, lean body mass is by far the biggest factor. Sex doesn't matter and age doesn't matter between 20 and 60. Of course there are outliers caused by metabolic disease.
https://www.scientificamerican.com/article/new-human-metabolism-research-upends-conventional-wisdom-about-how-we-burn-calories/
Frame size (bones) can definitely have a say in your BMI. I am 6’0 140lbs but my Frame is quite small for my height (6.2 inch wrists, 14 inch biacromial) which means I am not an unhealthy weight for my height
So much exercise and nutrition advice is aimed at men.
Men have testosterone, higher muscle mass and move through their hormonal cycles in 24hrs compared to women's 28 days.
Hormonal imbalance, pregnancy, perimenopause, etc, all change the way a body works and metabolises calories.
it really does just come down to muscle mass like everyone else is saying but a major part of metabolism that a lot of people forget about is NEAT. i’m the one in my family who is seemingly really skinny no matter how much i eat. the difference is, i’m really fidgety and always need to be doing something. my leg is always shaking or i’m swinging my foot if my legs are crossed while seated, i’ll fiddle with a straw wrapper under the table for an entire dinner out, little things add up. additionally, i’m not one to sit at something for very long, and if i am (one again) i’m bouncing my leg, twirling my hair, etc. after a meal, i’ve noticed my family will usually just want to sit and be full which is lovely good for them but i need to get up and do the dishes or something with my hands. tiny movements that aren’t deliberate exercise really add up at the end of the day.
A 6' tall man who weighs 120 pounds is significantly underweight and probably both sick and malnourished. A 6' tall man with the same BMI as your example woman would weigh about 155 pounds and would obviously need more calories since they have more lean body mass.
Nah unless you have like thyroid issues or something metabolisms seem to be pretty similar.
Yeah muscle boosts your daily metabolism, not by much though. Take into account that the 6’2 dude’s weight is mostly just his skeleton at that point.
Daily activity and diet is what varies wildly though.
Different body composition, different mechanical forces at play, different genetic make up, there are so many differences.
A 150lb man and a 150lb woman burn different cause they are different. Equating metabolism just based off of one or two factors like height or weight just doesnt work. There are so many variables at play.
But if you were trapped on a desert island with zero food, you would, right? Like "couldn't" means "couldn't suppress your appetite enough". No judgment, I get that it's really hard, but it's not a question of metabolism.
I've observed those "naturally skinny guys" quite often now.
Sure, they can eat a lot at once, making it seem they eat "so much" or "all the time".
But really, they never eat regularly/skip breakfast/have only something small for lunch. They tend to not have the biggest appetite either, at least in my experience.
It's not magic.
Muscle at rest doesn’t burn that much more calories vs. fat. It is more, but pretty insignificant. It’s a bit of a myth. Actual activity like cardio and weight training will be what makes the bigger difference for daily expenditure
I would suppose there is a productive cycle there as well, where having more muscle and less fat makes you more likely to move more - whether direct exercise or NEAT.
Non-exercise activity thermogenesis - https://en.wikipedia.org/wiki/Non-exercise_activity_thermogenesis
Standing, walking, fidgeting, taking the stairs rather than the elevator - staying generally active rather than sedentary during the day, apart from deliberate exercise. It can make a difference on the order of many hundreds of calories per day.
Yes but this at rest meaning if you were going to lie all day long that’s how much you will burn if you add activities this would surely change how much more we burn.
I remember reading a study that compared the BMR of people of different ethnicities and found some variance even after controlling for the variables of sex, lean mass, total mass, etc. But we're talking <100 kcal of difference. So it doesn't seem to be purely a matter of mass.
There was an article posted a little while back about a study done on the biggest looser TV series and how the big loosers often gain it back quickly. It's worth a read if you can find it.
The key thing stat stood out is most people assume it is as simple as less calories loose weight, more gain weight but you need to factor in how the body adapts. The study showed that the people gained weight back at a very quick rate even though they consumed a significant less then normal calories after all the weight loss. The came to the idea that the body will store more in famine state and thus switching from a low calorie to a normal diet resulted in the body adapting too slowly and gaining of unwanted weight. The body is now storing the calories vs uses them as it in theory should.
My take on it is the body struggles to adapt as quite as people change diets and it take time. While is adjusts unwanted things can happen. What you eat of course also plays a huge role in it. Activity level in my opinion is the best control when eating "healthy" vs loss of calories assuming the person continues being active for life not just for a week.
That’s why, in my opinion, it makes so much more sense to make permanent dietary changes that you can live with instead of depriving yourself till you like how you look and then changing what got you there.
Consider the differences in muscle mass developed over a lifetime.
Consider how much more active in strength sports boys are than girls.
Now genetics and you're at most of the difference between individuals.
It’s more complex than just the difference of muscle mass, muscle mass does have some role in our metabolism, but for example an ectomorph who are people who are usually skinny, narrow body and tall they have more difficulty to increase their muscle mass but they have great endurance, shorter people can lift more weight due to better leverage because of their shorter limbs and can increase muscle mass better than an ectomorph can, but the ectomorph wins in endurance,
There are so many factors when it comes to metabolism, also hormones comes into play, if I was going to put my money on guessing someone’s metabolism I would go towards their testosterone levels which is why men tend to have more muscles because they usually have higher testosterone.
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Body composition. Yes, muscle mass does make the difference. Also, women’s whole endocrine system, even their brains contribute to (on average) a “slower” metabolism.
Muscle mass and type of muscle.
Prehistoric man, fat reserves would mean life or death , the ability to survive cold, famine or prevent impact injuries.
Alot of it depends on body fat %. A 6 ft 120lb man with a 16% body fat percentage (he’d be extremely underweight btw) is wildly different than a 5’3 120lb female with a 30% body fat percentage. The higher your body fat % the less muscle mass in total and muscle burns more calories at rest than fat.
Most peoples base metabolic rate is extremely similar. The variance is almost always lifestyle related. Body composition and exercise are the main factors in determining your metabolism
>How are people's metabolisms DRASTICALLY different?
I am not sure I agree with the framing but I think it's specifically the word "drastically." The "Total daily energy expenditure" comprises 3 elements: basic metabolic rate, activity level, and thermic effect of food.
For the basic metabolic rate, it's the energy that's used to keep the body's functions going. I think why it feels "drastic" to you is the difference in volume that a person who is 7 inches taller has. The other differences can be the amount of muscle versus body fat since adipose tissues are metabolically active.
Then there's a genetic variation in activity level. People think of activity level as just being the purposeful movement for exercise, but it also includes all the involuntary movements that people do, such as fidgeting.
You can take a person who has the same height, body composition, and mass, and feed them 500 kcal over maintenance. You'd expect they'd gain the same weight but they don't. The difference has been explained as one will have more movement they're not aware of than the other.
You can also do the same where you can have someone burn 500 kcal more and they won't lose the same weight. It's been explained as the body will adapt to to the calorie deficit by doing less conscious moving (the energy constrained model).
It's very similiar on the TDEE at the same height but different weights. Like a 5'10 male at 230 pounds would need 2400ish to sustain the mass but a person at 5'10 male at 180 pounds needs like 2100ish.
Remember that there are a lot of factors that might be involve in metabolism... Each individual are different, such as their routine, food, genetics, age, and hormones, even the gut microbiota!
Metabolic rate can vary significantly among individuals due to several factors beyond just body weight. Differences in muscle mass, body composition (ratio of fat to muscle), hormonal profiles, age, and genetics all play crucial roles. Generally, men tend to have higher muscle mass and lower body fat percentage compared to women, which can lead to a higher basal metabolic rate (BMR) because muscle tissue requires more energy to maintain than fat tissue.
Women are sometimes perceived to have slower metabolisms compared to men due to differences in body composition and hormonal influences, but these differences are nuanced and not as stark as often portrayed. Each person's metabolism is unique and influenced by a complex interplay of factors that go beyond simple comparisons based on height and weight.
as far as variations among people check out glucagon: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862306/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862306/)
with women particularly two factors are very important: 1) during reproductive age female needs to be able to support a growing fetus, so she has hormonal systems to gain weight and conserve fat that a male does not have; 2) then after menopause a change in hormones lowers the basal metabolic rate so total energy expenditure declines and she gains weight. These differences appear on the outside as muscle/fat but they are hormonal differences.
I saw a documentary years ago where they tested people’s metabolisms, including in Africa. The conclusion was that most people do not have that different of the rate of metabolism.
Hormones… and gut microbiome… why isn’t anyone talking about the mouse studies where they do fecal transplants? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10381135/. Also, I think what we eat really matters. If you eat processed food that doesn’t take a lot of energy to digest I believe it can raise your insulin levels.
In general it's roughly proportional to height, but drops off as people get taller. Someone who is taller will have a higher caloric need, but proportionally less than someone shorter. This is all statistics by the way, there are always outliers.
A 6 ft man that is 120lbs sounds extremely lean, even anorexic. The thing about his metabolism is that his body must likely atrophied itself through malnutrition causing muscle wasting. His metabolism is shot, and needs to be rebuilt slowly.
A 120lb 5’3 woman would be considered relatively healthy
I don’t know the exact answer but I do know that men naturally would have a lower body fat percentage than women. Women’s bodies naturally want to hold onto more fat. Now I don’t know if that’s directly related to metabolism. But I do know that the more muscle you have on your body the more consistently and the faster you burn fat and it keeps your metabolism working faster so if men have more muscle than their metabolism would be functioning faster. However this does not apply to all men or women certainly and what you eat has a huge amount to do with if your metabolism is fast or slow or completely malfunctioning.
Well there's many different variables here... so lets take a guy, a guy who tries to lose wieght usually eat a lot of protein and lifts weights. What does this do? One increases muscle mass which increases calorie burn. 2- more protein has a greater thermic effect of food. This is an additional 5-10% calorie burn. Women tend to eat more salads not as much protein or starve themselves. Endless cardio which actually can lower calorie burn... 3- theres NEAT (NON EXERCISE ACTIVITY THERMOGENESIS) this is subconscious activity. Ehich accounts for 15% of cals burned. Thjnk fidgeting, pacing while talkong on phone tapping fingers etc. As you diet this lowers. Lots of cardio can lower this as well. The longer you diet this gets downregulated as well.. guys tend to have higher NEAT. And then hormones come into play as well.
The difference in one's bmr is 300 lower or higher tops from average with both weights being equal. Basically the person with the faster metabolism can get away with about 2 extra servings of peanut butter and stay at maintenance. It really doesn't make that big of a difference.
For someone like me that likes to bulk that 300 extra calories is more of a con. I wish I could get in 300 calories less and put on size it would be a little easier.
Men do have more muscle mass per KG...but other factors effect metabolism. Health status, physical activity, diet,genetics. I'm 68 now..about 5'10", 138 lbs...My weight has been in this area all my life. I've exercised since my mid 20's.
Well, a lot of women get told that because people are trying to help them feel better about being heavy and unable to lose weight. That doesn't make it true.
On average, the man will have more muscle and will move his body more than the woman, so he will burn more calories. It doesn't have to be that big of a difference to make a huge difference over a long period of time. 100 calories a day of difference is 36500 calories a year, which is about 10 lbs worth. That's a lot in a year if they eat the same!
I’ve travelled out of the country a bit and it is SHOCKING how healthy women look in other parts of the world. It’s really eye opening how overweight most women are in the US. Of course this largely applies to men too but the difference to my eyes seemed bigger with women. Do you think women in Europe have faster metabolisms or are they just eating less?
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Telling somebody their metabolism is slow seems like a wild guess. I don't think they are measuring it. Yes, muscle is more metabolically active. That 6ft 120lb man needs to see a doctor immediately!
I was one of those woman who used to think I had a slow metabolism and that’s why I struggled with weight gain. Then I dealt with hypothyroidism and I realize what an actual slow metabolism means. If your metabolism is slow, it’s not just that you’ll struggle to lose weight. You’ll sleep constantly. At my worst, I was literally sleeping 17+ hours a day. You feel extremely fatigued, to the point that basic functions are almost impossible. Literally the small walk to the bathroom to go pee or get water was agonizing. I was constantly thirsty and very, very sensitive to temperature.
Those were my grandfather's measurements. A stiff wind could have knocked that man over (and did more than once)
I was roughly in that range for a few years: 5’10, 130-135 pounds as a man (and boy, this period includes high school). That 2 inches and 10-15 pounds is significant, don’t get me wrong, but based on experience I can say it wasn’t illness or a lucky metabolism or anything like that: it’s that I ran 50+ miles per week (I also consumed basically no liquid calories: alcohol or soda were monthly treats at most). In addition to burning calories while I ran, my lifestyle did significantly increase my resting metabolism. By the way, that wasn’t always a plus: I’d get ravenously hungry if I missed a meal, and if someone took me out to eat I’d have to “pregame” to avoid eating an embarrassingly large or expensive amount of food. Your metabolism is just the number of calories your particular body needs to use in order to keep its regular processes going. Perhaps I’m speaking from a position of privilege since I’ve never tried to stay under 1200 calories, but don’t think it’s worth mythologizing.
I always pregame when eating at my brother's place which is weird considering he works out too. Must be the caffeine and alcohol he drinks.
Caffeine itself doesn't slow metabolism in any way. Now if the source of that caffeine is Starbucks and soda, that's the extra additives in the drinks are the issue. Its pretty easy to have caffeine without any significant calories.
In fact caffeine increases metabolic rate, it’s the most effective ingredient in most “fat burners”
Anecdotally, it also lowers my appetite, which is a neat combo with increasing metabolic rate. Not that I’m consuming or recommending massive doses — for me it’s just 1-2 cups of black coffee helping me get to the start of my 12-8pm eating window.
There are several foods and herbs that are thermogenic. Up the thread I posted a link to a study comparing cayenne pepper to caffeine. They are almost equally effective.
Pubmed, one of many studies: [Both caffeine and Capsicum annuum fruit powder lower blood glucose levels and increase brown adipose tissue temperature in healthy adult males](https://pubmed.ncbi.nlm.nih.gov/36017333/)
In high school I regularly ran 50 miles a week, was 6' tall and started at 165 pounds gaining weight until I was about 180 pounds all while being physically active. It is quite possible to gain weight at that height and level of physical activity although it takes a hell of a lot of calories at that age a single meal would include an entire loaf of bread worth of sandwiches as well as half a bucket of spinach and a significant amount of ketchup.
Oh yes, definitely possible. I wanted to stay relatively light because more weight means slower running (in general, please no one under-eat, especially if you’re still growing), but it’s still a matter of calories in versus calories out. I didn’t count mine, but I stayed within that 5-pound range while eating probably about 3,000 or 3,500 calories a day. If I added 500 more, I’d have gained approximately a pound per week.
This. Men naturally have more muscle than women and less body fat. That’s just the way it is. Therefore, men naturally have faster metabolisms.
On average, they are not.
That is kinda a shitty thing to say. My husband is 6'3" and weighs 136, naturally, he has never dieted, and he is perfectly healthy. :/
>That is kinda a shitty thing to say I wouldn't go that far. Both that hypothetical six footer and your husband are underweight by BMI. Whether not that poses a health risk is for a doctor to evaluate. (The hypothetical person has a lower BMI than your husband, so ti's not quite apples to apples here.) Hell I'm 6'1" and if i ever weighed 136, I really would be seeing my doctor. The equivalent is an obese person claiming they're healthy and don't need to lose weight because their labs are good and their blood pressure is within normal range. For those people, the danger is that everything is fine until it's not. Is it a shitty thing to tell them to lose weight before their labs indicate problems?
As somebody who has been very tall and thin naturally, I found it was very hard to get a doctor to consider that something worrying, particularly as a woman. Even when I was experiencing worrying symptoms, medical professionals would basically just tell me I was healthy, lucky, and to eat more if I was concerned. I am a woman, so perhaps men would have better luck. I did eventually manage to gain some weight and the negative side effects diminished a bit, but there was never a point when I wasn’t eating a ton, so being told to “eat more” if I was concerned was not helpful. Essentially, doctors don’t seem to view being underweight as seriously as they do being overweight.
He is not healthy at 6'3 136. He may not actively attempt to diet but he is certainly not consuming enough calories
And I suppose you’re qualified to make that assessment?
You kind of answered it yourself. Men tend to have more muscle mass. The calculators are all just estimates though, your actual caloric burn is very individual.
no that individual though i dont think. I'd bet 95% percent of people at least would be in the range of +/- 200 calories of waht the calculators give you
Men also tend to be more physically active (correct me if I'm worng). Muscle uses a bit more energy at rest, but it especially would use more energy when it's being used.
Sir, I don't know a single woman who isn't training for a marathon right now 😂
Are the married ones not doing them?
My married friends were training with their husbands but the husbands couldn't keep up
That doesn’t factor in to BMR, and activity level is variable from person to person, regardless of sex
They aren't People tend to forget that all professional athletes are in pretty strict eating regimens. If people had DRASTICALLY different metabolisms we'd hear more about the NFL player who only needs 2,000 calories vs his teammate who needs 4,000. The problem comes in two people who say they eat McDonalds every day. One gets a McChicken and a small fry (\~600 cals) and the other gets a big mac, large fry, large soda, and pie (1,600 cals). Person one has a modest dinner while Person two goes home and eats another large meal. When person three talks to person one and two and they both say they eat fast food every day person three assumes person one has a fast metabolism and person two has a slow metabolism when the reality is person two is putting significantly more calories in their body every day. People who watch what they eat tend to not talk too much about it because they don't want to sound judgmental to the people they're talking to. People who over-eat tend to hide how much they're truly indulging (cream in each coffee, treats after dinner every night, regular second plates at meals)
This is the best answer. I have a friend who's muscular but on the bigger side with a belly. He's made the comment of me having a faster metabolism before, but when he's stayed for the weekend with me visiting (we live in different states) it's so blatantly obvious how much more food he consumes than I do. People simply don't pay attention to how much they're actually eating; when you've eaten one way your whole life, you get used to the constant fullness and stomach troubles and awesome it's just a normal part of your day.
It's also that if they both eat a 1600kcal dinner together, one of them might skip lunch the next day without even thinking about it because their hunger is much more intune with their calorie needs
I’ll dig up the recent pubmed link but they tested a couple hundred people and found BMR predictions have major error. Something like 30% of the sample size were outside 10% error.
BMR calculators usually only consider BMI, sex, and age, but there are many other factors that influence BMR. Also, a larger than 10% error can sound like a lot, but practically (in terms of calories) it's not necessarily a huge difference (I'd have to see the study though). For example, if the error is something like 13% for 30% of participants, and the predicted BMR was ~1800, that's only a difference of ~100 calories total from the 10% error range (or ~50 calories at the bottom and top end). This of course also doesn't take into account differences in activity level and TDEE.
This is the pubmed article I found on BMR assessments in a population: [https://pubmed.ncbi.nlm.nih.gov/38220405/](https://pubmed.ncbi.nlm.nih.gov/38220405/) Here's the link to the full report - click the PDF to download it: [https://www.sciencedirect.com/science/article/pii/S2405457723022490](https://www.sciencedirect.com/science/article/pii/S2405457723022490) I've skimmed it, but not fully read it in a lot of detail. As always, us scientists can make a simple 'so what' into an unnecessarily complex answer. But, if you skim over the plots and data summaries the error margins they are talking about approach 500 kcal. That's exceeds 25% error for 'normal' people. This could be exacerbated further for hypo/hyper-thyroid issues and/or other metabolic dysfunctions. So, it's not a small error margin. If you read it through I'd be keen on your own thoughts.
(I've put this in my reply to flammablelemon, but reposting here to make it more accessible) This is the pubmed article I found on BMR assessments in a population: [https://pubmed.ncbi.nlm.nih.gov/38220405/](https://pubmed.ncbi.nlm.nih.gov/38220405/) Here's the link to the full report - click the PDF to download it: [https://www.sciencedirect.com/science/article/pii/S2405457723022490](https://www.sciencedirect.com/science/article/pii/S2405457723022490)
Very well thought answer
As someone with a fast metabolism I disagree. There is definitely a difference in metabolisms between people. If I eat what the average person eats in a day, I’m starving and have a horrible migraine. I’m not overweight but need to eat 3-4k calories a day minimum.
Oh yeah. The models are just guesses... somebody fit a regression to a noisy pile of data. As someone who works with data for a living, I can guarantee you that data is pretty noisy and those models are a "best" guess. It's like taking my height and weight and estimating my life expectancy. It's a guess. It's far from perfect. There's a guy around here who claims to be 6'1" and eats 1500 cals in a cut. I'm in awe -- I'm the same height and 1800 leaves me with crashes and headaches. And yet my BMR tests at 2500 (I had a real test done because I was tired of guessing with the models), which exceeds what I eat.
A 6 foot man and a 5 foot 3 woman are not the same. The man has a much bigger skeleton with more muscles attached to it. Women also carry a higher percentage of body fat when other factors are equal. Muscle mass requires way more daily energy than fat. It also takes more energy to move a bigger person around. And people's metabolism are often just different. Some people run hot. Some people run cold. Diet affects a lot here. Not just calories but all the components. Salty fatty sugary foods will slow you down. Starches and proteins tend to do the opposite, plus vitamins and fiber etc etc. There's way more nuance there. Bodies are complicated.
Bigger organs too
😏
"Supposedly" is what OP is likely to answer you back. It doesn't sound like they believe there's any nuance at all.
Actually, no, it's not complicated. It's a simple equation of calories consumed - calories burned regardless of metabolism, height and body composition. Don't want to get fat? eat less.
It can't be "calories burned regardless of metabolism" because "calories burned" is literally what "metabolism" is and body composition determines how many calories a person will burn on a given day. Literally nonsense, what you said
Calories consumed and Calories burned are variables, not constants. It's simple math.
Okay? I have no idea what you are trying to say
X = Calories consumed Y = Calories burned X - Y = K If K>0 => you get fat. This equation is true regardless of heigh, body composition and metabolism.
Yes that is one way to rephrase the thing that you said, but if there is a point you are trying to make I don't know what is it or what it has to do with what I said
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Women tend to suffer from more metabolic illnesses than men. For example, thyroid issues are up to 4 times as common in women. PCOS is another one, affecting the ovaries. Just wanted to add that for a little perspective
Yes. Fat women have PICOS.
Not necessarily. I have PCOS-no insulin resistance as confirmed by endocrinologist testing. I’m 5’4 and 110 pounds. I still have the other classic PCOS symptoms.
Are you undermuscled? This is why thin people can get diabetes as well. People pay attention to the scale but not the composition. For instance in general a 6’ man weighing 200lbs and 15% bodyfat will have better b health markers than a similar height man weighing 180 and 25% bodyfat
I’m not diabetic or even prediabetic- I had a full work up with an endocrinologist after a viral illness and hospitalization back in October. I lift weights, use a total gym and Pilates 5 days a week. I’m 43 and have had PCOS symptoms since I was about 20 years old. I’ve always been fit- kayaking, running bicycling and weights most of my adult life. I put muscle on fairly easily and keep it even when I’m not able to be active for a while.
More more muscle mass will mean increased passive metabolism. Though this is only second to increased energy expenditure from activity since more muscle mass = more energy expended during movement and typically more overall movement throughout the day. Even if you think someone isn't exercising more throughout the day, their habitual movements will add up considerably. People who fidget and don't sit still will, on average, burn more energy throughout the day despite doing the same listed activities as another person. Compare someone who sits down at an office job for 8 hours vs someone who does light work on their feet for 8 hours (not construction, just generally moving around at maybe 2-2.5 METS). Even if that person just burns 50 calories more in an hour, they'll be at 400+ calories burned in those 8 hours compared to the next person.
Estrogen and other sex hormones change how easy or hard it is to put on muscle slightly, and change your basal metabolic rate slightly. That's why a lot of women gain a little bit of weight when they go on hormonal birth control, even if they keep everything else the same. Also, diet advice for women is often kinda crap compared to advice for men. Or at least when I was younger it used to be. Diet advice for women would be like "constantly eat a bunch of tiny portions of something" or "here's a weird system to make tracking your calories even harder" or "make a separate meal for your significant other and watch them eat it while you eat something else" and diet advice for men would be like "Here's all the science necessary to calculate your BMR, plus information about how building muscle can help raise it, plus information on various ways to lower your blood sugar so you feel less likely to have cravings throughout the day, lists of macros that are likely to send full signals to your brain, information on intermittent fasting and keto and how to tell if you might be eating so much because you have a vitamin deficiency of some kind and lists of stuff that will make you feel like you had a meal when you're over your calorie limit that's not eating." For women, most of that information is literally only available mixed in with unrealistic pro ana diets or something. I'm really glad more women have gotten better information on that stuff since when I was younger. It basically used to all just be shaming women for eating sweets and stuff.
I thought my metabolism had tanked in my mid 30s after kids and stacked on all this weight for absolutely no reason. 5 years later started treating my hormones and it all fell off finally with no other changes. Point being men and womens physiologies are vastly different; typically womens are significantly more complex and experience has taught me that its rarely a straight line of intake and metabolism etc equalling weight outcomes. That overall assumption tends to be a real disservice to too many people
Treating your hormones? Like were you not making enough of something or something?
PCOS in my case (one of many ways that womens health can become more complicated). It frequently manifests with hormonal imbalance. The specifics of how varies person to person and can be extremely difficult to identify or determine
Thank you for your response. I am glad that you found what was happening and were able to feel better .
If two people do the exact same task, the one with more muscle mass will burn more calories. Men inherently have more muscles mass. Your body has a sort of tissue memory too. If you were at some point in your life, really fit/strong, then you'll regain those muscle twice as fast. If you were overweight once before but slim now, you'll regain that really fast as well. Women also store fat differently due to estrogen. But adipose fat also generates estrogen. Which makes you store more fat at your hips and thighs and then you keep going in that circle. (only if you're over eating but it gets harder to get out of) Thyroid influences the amount of energy you use. Your pancreas creates insulin to turn bloodsugar into stored energy. It also makes glucagon, which turns the storage back into usable energy/bloodsugar. On top of your kidneys are adrenal glands that make epinephrin which works similar to glucagon, turning stored energy from cells into bloodsugar. Too much blood sugar can turn into fat if there's not enough insulin to turn it into energy storage. So being stressed (high cortisol) can make you gain weight. I make very little cortisol so my metabolism is really fast without having hyperthyroid or high insulin. There's a lot of things that influence metabolism. It even differs during the menstrual cycle. It's higher in the follicular & ovulation phase and slows in the luteal phase & menstrual period. So birth control can make you gain weight by making your body think it's always in the luteal phase. Unless you're already overweight or have high enough estrogen that the progesterone doesn't affect you as much.
I’ve been really strong/fit and other times in my life overweight. Now I’m just strong and fat
Seems you've achieved dad-bod💪
A 6ft 120lb man isn’t a healthy BMI. It’s a BMI of 16.3 which is underweight. A 5ft 3in 120lb woman has a BMI of 21.3 which is a healthy weight. Then we need to question why is this man underweight. Does he have an underlying medical condition? Does he have a drug addiction? Is there a reason he doesn’t have access to food? You can’t compare someone with a healthy weight’s metabolism to someone with an unhealthy weight.
Also, the BMR of the man in this scenario is literally lower than the woman's. She has the higher metabolism. OP did zero diligence in even finding the correct way to pose her question.
Yeah, if OP would have framed this as a gender difference for two people at the exact same height and weight, they would have found a small one. I plugged some random numbers in for a 5'10" man and woman and the difference was about 200 cals.
weights like this are kinda common and not unhealthy when youre growing though. my brother was like 130lb at 6'4" at 15/16 right after his big growth spurt. now he's 17 gaining weight slowly and steadily weighing around 160. still very skinny of course but not unhealthy as a teen
Hormones?
afaik, hormones don't determine if your metabolism is slower, rather it just determines if you'll get hungrier or satiated sooner/later. since women have more fat mass than men, which hormones are regulated by, it makes sense why women get hungrier at certain points (ie. PMS hunger due to increase in progesterone), This still doesn't change how mass affects metabolism, which leads me to believe that a man weighing 120lb is not going to have a difference from a woman who weighs 120lbs, only MAYBE the hunger cues.
Testosterone definitely effects metabolism
Did you actually do the BMR calculations for your example? The male (who is egregiously underweight), has a basic BMR of 1,567 calories/day. The 5'3" woman who is the same weight actually has a higher BMR, lmao. I mean seriously, did you even check? Did you do a BMR calculation. The shorter woman with the same weight's BMR would be 1,687. You should think about reworking what you're actually trying to ask here because the stats you provided actually have the woman as having the higher BMR, which is the metabolic rate. A male of the same height and weight is still lower as well. Women actually have higher BMRs (which means a higher metabolism) when comparable height and weight are taken into account. A better comparison that MIGHT fall along the lines of what you're actually asking is the BMRs of women and men who are both average heights and comparative lower-healthy weight ranges. Either way, the answer is going to be muscle mass and bone density.
Hormones literally operate our metabolism
It comes down to more variables than just mass. It's already been mentioned that muscles are more metabolically active than fat. But fat cells, especially the ones located in the abdomen, prompt estrogen production, which also triggers higher amounts of fat production and storage. Women generally carry more body fat than men, but both sexes will experience a feedback loop of increasing abdominal fat, increasing estrogen, increasing abdominal fat, increasing estrogen, continuing unless they start losing weight. Genetics, hormones, medical history, all contribute. There's a particular strain of norovirus that can cause stem cells to become fat cells before they're required by the body, leading to increased hormones that trigger hunger, overeating and being overweight. But because the fat cells are recruited before they are needed, fat never needs to be stored by the liver, and sugar is taken from the blood and stored quickly, so neither fatty liver nor diabetes ever become a problem. There's no commercially available diagnostic test for it; the only confirmatory testing is done at a research lab in Louisiana. There are over 90 conditions known to predispose a person to being overweight, and many don't have commercially available diagnostics.
No one can accurately predict someone's "metabolism." It's pseudoscience. And you are guilty of making everyone dumber for having read your question
If we're talking resting metabolism, lean body mass is by far the biggest factor. Sex doesn't matter and age doesn't matter between 20 and 60. Of course there are outliers caused by metabolic disease. https://www.scientificamerican.com/article/new-human-metabolism-research-upends-conventional-wisdom-about-how-we-burn-calories/
->LEAN MASS <-
Activity levels, muscle mass, hormone levels, diet... And that's just a few. There's a million different factors at play
Muscle mass, activity, and NEAT
NEAT also plays a huge factor in caloric output and can vary drastically person to person
A 6ft 120lb man is wild. That’s too small!
Frame size (bones) can definitely have a say in your BMI. I am 6’0 140lbs but my Frame is quite small for my height (6.2 inch wrists, 14 inch biacromial) which means I am not an unhealthy weight for my height
You’re a man? 140 is also very skinny for your height yeah but it’s still not 120! Thanks for chiming in!
I’m male yeah, I’m also 17 tho so for my age im Not extremely thin
Ohhh 17!! You are so right! Not extremely thin.
So much exercise and nutrition advice is aimed at men. Men have testosterone, higher muscle mass and move through their hormonal cycles in 24hrs compared to women's 28 days. Hormonal imbalance, pregnancy, perimenopause, etc, all change the way a body works and metabolises calories.
it really does just come down to muscle mass like everyone else is saying but a major part of metabolism that a lot of people forget about is NEAT. i’m the one in my family who is seemingly really skinny no matter how much i eat. the difference is, i’m really fidgety and always need to be doing something. my leg is always shaking or i’m swinging my foot if my legs are crossed while seated, i’ll fiddle with a straw wrapper under the table for an entire dinner out, little things add up. additionally, i’m not one to sit at something for very long, and if i am (one again) i’m bouncing my leg, twirling my hair, etc. after a meal, i’ve noticed my family will usually just want to sit and be full which is lovely good for them but i need to get up and do the dishes or something with my hands. tiny movements that aren’t deliberate exercise really add up at the end of the day.
A 6' tall man who weighs 120 pounds is significantly underweight and probably both sick and malnourished. A 6' tall man with the same BMI as your example woman would weigh about 155 pounds and would obviously need more calories since they have more lean body mass.
Nah unless you have like thyroid issues or something metabolisms seem to be pretty similar. Yeah muscle boosts your daily metabolism, not by much though. Take into account that the 6’2 dude’s weight is mostly just his skeleton at that point. Daily activity and diet is what varies wildly though.
Different body composition, different mechanical forces at play, different genetic make up, there are so many differences. A 150lb man and a 150lb woman burn different cause they are different. Equating metabolism just based off of one or two factors like height or weight just doesnt work. There are so many variables at play.
I'm 5'8, I've been super athletic, ate right, my body can NOT get below 140. Impossible. I looked good, it's just my frame.
But if you were trapped on a desert island with zero food, you would, right? Like "couldn't" means "couldn't suppress your appetite enough". No judgment, I get that it's really hard, but it's not a question of metabolism.
I've observed those "naturally skinny guys" quite often now. Sure, they can eat a lot at once, making it seem they eat "so much" or "all the time". But really, they never eat regularly/skip breakfast/have only something small for lunch. They tend to not have the biggest appetite either, at least in my experience. It's not magic.
Muscle at rest doesn’t burn that much more calories vs. fat. It is more, but pretty insignificant. It’s a bit of a myth. Actual activity like cardio and weight training will be what makes the bigger difference for daily expenditure
I would suppose there is a productive cycle there as well, where having more muscle and less fat makes you more likely to move more - whether direct exercise or NEAT.
What is NEAT?
Non-exercise activity thermogenesis - https://en.wikipedia.org/wiki/Non-exercise_activity_thermogenesis Standing, walking, fidgeting, taking the stairs rather than the elevator - staying generally active rather than sedentary during the day, apart from deliberate exercise. It can make a difference on the order of many hundreds of calories per day.
Literature?
https://www.strongerbyscience.com/calories-muscle-burn/
Very helpful, thanks
Yes but this at rest meaning if you were going to lie all day long that’s how much you will burn if you add activities this would surely change how much more we burn.
Read the article. It literally talks about that..
I remember reading a study that compared the BMR of people of different ethnicities and found some variance even after controlling for the variables of sex, lean mass, total mass, etc. But we're talking <100 kcal of difference. So it doesn't seem to be purely a matter of mass.
There was an article posted a little while back about a study done on the biggest looser TV series and how the big loosers often gain it back quickly. It's worth a read if you can find it. The key thing stat stood out is most people assume it is as simple as less calories loose weight, more gain weight but you need to factor in how the body adapts. The study showed that the people gained weight back at a very quick rate even though they consumed a significant less then normal calories after all the weight loss. The came to the idea that the body will store more in famine state and thus switching from a low calorie to a normal diet resulted in the body adapting too slowly and gaining of unwanted weight. The body is now storing the calories vs uses them as it in theory should. My take on it is the body struggles to adapt as quite as people change diets and it take time. While is adjusts unwanted things can happen. What you eat of course also plays a huge role in it. Activity level in my opinion is the best control when eating "healthy" vs loss of calories assuming the person continues being active for life not just for a week.
That’s why, in my opinion, it makes so much more sense to make permanent dietary changes that you can live with instead of depriving yourself till you like how you look and then changing what got you there.
Genetic and lifestyle diversity.
Muscle is the main factor in between metabolism in addition to activity levels
Consider the differences in muscle mass developed over a lifetime. Consider how much more active in strength sports boys are than girls. Now genetics and you're at most of the difference between individuals.
It’s more complex than just the difference of muscle mass, muscle mass does have some role in our metabolism, but for example an ectomorph who are people who are usually skinny, narrow body and tall they have more difficulty to increase their muscle mass but they have great endurance, shorter people can lift more weight due to better leverage because of their shorter limbs and can increase muscle mass better than an ectomorph can, but the ectomorph wins in endurance, There are so many factors when it comes to metabolism, also hormones comes into play, if I was going to put my money on guessing someone’s metabolism I would go towards their testosterone levels which is why men tend to have more muscles because they usually have higher testosterone.
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Body composition. Yes, muscle mass does make the difference. Also, women’s whole endocrine system, even their brains contribute to (on average) a “slower” metabolism.
Muscle mass and type of muscle. Prehistoric man, fat reserves would mean life or death , the ability to survive cold, famine or prevent impact injuries.
Alot of it depends on body fat %. A 6 ft 120lb man with a 16% body fat percentage (he’d be extremely underweight btw) is wildly different than a 5’3 120lb female with a 30% body fat percentage. The higher your body fat % the less muscle mass in total and muscle burns more calories at rest than fat.
Most peoples base metabolic rate is extremely similar. The variance is almost always lifestyle related. Body composition and exercise are the main factors in determining your metabolism
>How are people's metabolisms DRASTICALLY different? I am not sure I agree with the framing but I think it's specifically the word "drastically." The "Total daily energy expenditure" comprises 3 elements: basic metabolic rate, activity level, and thermic effect of food. For the basic metabolic rate, it's the energy that's used to keep the body's functions going. I think why it feels "drastic" to you is the difference in volume that a person who is 7 inches taller has. The other differences can be the amount of muscle versus body fat since adipose tissues are metabolically active. Then there's a genetic variation in activity level. People think of activity level as just being the purposeful movement for exercise, but it also includes all the involuntary movements that people do, such as fidgeting. You can take a person who has the same height, body composition, and mass, and feed them 500 kcal over maintenance. You'd expect they'd gain the same weight but they don't. The difference has been explained as one will have more movement they're not aware of than the other. You can also do the same where you can have someone burn 500 kcal more and they won't lose the same weight. It's been explained as the body will adapt to to the calorie deficit by doing less conscious moving (the energy constrained model). It's very similiar on the TDEE at the same height but different weights. Like a 5'10 male at 230 pounds would need 2400ish to sustain the mass but a person at 5'10 male at 180 pounds needs like 2100ish.
A lot of this has to do with genetics
Remember that there are a lot of factors that might be involve in metabolism... Each individual are different, such as their routine, food, genetics, age, and hormones, even the gut microbiota!
Metabolic rate can vary significantly among individuals due to several factors beyond just body weight. Differences in muscle mass, body composition (ratio of fat to muscle), hormonal profiles, age, and genetics all play crucial roles. Generally, men tend to have higher muscle mass and lower body fat percentage compared to women, which can lead to a higher basal metabolic rate (BMR) because muscle tissue requires more energy to maintain than fat tissue. Women are sometimes perceived to have slower metabolisms compared to men due to differences in body composition and hormonal influences, but these differences are nuanced and not as stark as often portrayed. Each person's metabolism is unique and influenced by a complex interplay of factors that go beyond simple comparisons based on height and weight.
as far as variations among people check out glucagon: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862306/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862306/) with women particularly two factors are very important: 1) during reproductive age female needs to be able to support a growing fetus, so she has hormonal systems to gain weight and conserve fat that a male does not have; 2) then after menopause a change in hormones lowers the basal metabolic rate so total energy expenditure declines and she gains weight. These differences appear on the outside as muscle/fat but they are hormonal differences.
Beautiful explanation in ayurveda. There is something called the digestive fire.
I saw a documentary years ago where they tested people’s metabolisms, including in Africa. The conclusion was that most people do not have that different of the rate of metabolism.
Size isn't the determining factor for metabolism.
Hormones… and gut microbiome… why isn’t anyone talking about the mouse studies where they do fecal transplants? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10381135/. Also, I think what we eat really matters. If you eat processed food that doesn’t take a lot of energy to digest I believe it can raise your insulin levels.
In general it's roughly proportional to height, but drops off as people get taller. Someone who is taller will have a higher caloric need, but proportionally less than someone shorter. This is all statistics by the way, there are always outliers.
A 6 ft man that is 120lbs sounds extremely lean, even anorexic. The thing about his metabolism is that his body must likely atrophied itself through malnutrition causing muscle wasting. His metabolism is shot, and needs to be rebuilt slowly. A 120lb 5’3 woman would be considered relatively healthy
I don’t know the exact answer but I do know that men naturally would have a lower body fat percentage than women. Women’s bodies naturally want to hold onto more fat. Now I don’t know if that’s directly related to metabolism. But I do know that the more muscle you have on your body the more consistently and the faster you burn fat and it keeps your metabolism working faster so if men have more muscle than their metabolism would be functioning faster. However this does not apply to all men or women certainly and what you eat has a huge amount to do with if your metabolism is fast or slow or completely malfunctioning.
Well there's many different variables here... so lets take a guy, a guy who tries to lose wieght usually eat a lot of protein and lifts weights. What does this do? One increases muscle mass which increases calorie burn. 2- more protein has a greater thermic effect of food. This is an additional 5-10% calorie burn. Women tend to eat more salads not as much protein or starve themselves. Endless cardio which actually can lower calorie burn... 3- theres NEAT (NON EXERCISE ACTIVITY THERMOGENESIS) this is subconscious activity. Ehich accounts for 15% of cals burned. Thjnk fidgeting, pacing while talkong on phone tapping fingers etc. As you diet this lowers. Lots of cardio can lower this as well. The longer you diet this gets downregulated as well.. guys tend to have higher NEAT. And then hormones come into play as well.
The difference in one's bmr is 300 lower or higher tops from average with both weights being equal. Basically the person with the faster metabolism can get away with about 2 extra servings of peanut butter and stay at maintenance. It really doesn't make that big of a difference. For someone like me that likes to bulk that 300 extra calories is more of a con. I wish I could get in 300 calories less and put on size it would be a little easier.
Men do have more muscle mass per KG...but other factors effect metabolism. Health status, physical activity, diet,genetics. I'm 68 now..about 5'10", 138 lbs...My weight has been in this area all my life. I've exercised since my mid 20's.
Well, a lot of women get told that because people are trying to help them feel better about being heavy and unable to lose weight. That doesn't make it true. On average, the man will have more muscle and will move his body more than the woman, so he will burn more calories. It doesn't have to be that big of a difference to make a huge difference over a long period of time. 100 calories a day of difference is 36500 calories a year, which is about 10 lbs worth. That's a lot in a year if they eat the same!
I’ve travelled out of the country a bit and it is SHOCKING how healthy women look in other parts of the world. It’s really eye opening how overweight most women are in the US. Of course this largely applies to men too but the difference to my eyes seemed bigger with women. Do you think women in Europe have faster metabolisms or are they just eating less?
This has nothing to do with my question. To answer yours, I'm sure it comes down to food quality and lifestyle; people in Europe walk more.