Gender Differences in Fat Metabolism
A few months ago, I addressed the role gender plays in how we respond to intermittent fasting. That post sparked a great discussion, and I’ve since received a fair number of emails from readers eager to learn other ways in which gender plays a role in our health and nutrition. One email in particular set me off on a round of research. So, a hat tip to you, Winifred, for giving me something to think, learn, and write about. I hope everyone finds it to be helpful.
As you may know, women and men store and metabolize fat differently from each other, and a 2008 paper (PDF) reviewed the evolutionary reasons for these differences. Here’s a summary of their findings and few other noteworthy factoids:
Women carry more fat than men. They are better at storing fat than men. Moreover, when women store fat, they do so in different places than men. They’ll preferentially store fat in in the hips, butt, and legs, whereas when men gain weight, it usually goes to the upper body (hence why you see massive beer bellies atop stick legs). Furthermore, when both men and women store upper body fat, men are more likely to develop visceral fat – the abdominal fat associated with metabolic syndrome – while women are more likely to develop subcutaneous fat.
On women, body fat seems to be healthier and less problematic. The characteristically female lower body “gluteofemoral fat” is actually a strong sign of metabolic health, whereas abdominal fat is not. In men, high body fat levels correlate strongly with insulin resistance, while this relationship is much weaker in women (probably because of their lower tendency to store visceral fat).
Women burn fat differently than men. Upper body fat goes first, while lower body fat tends to stay put. Except during pregnancy and lactation, when the lower body begins to give up lower fat stores far more readily. Interestingly (and not by coincidence), women tend to preferentially store the long chain omega-3 fatty acid DHA – the one that’s so important to the baby’s development during and pregnancy – in their thighs.
Women make more triglycerides than men do, but their serum levels are similar. This indicates that the fat is being taken back up into adipose tissue at a higher rate in women than in men.
Women are better at burning fat in response to exercise. During endurance exercise, they exhibit lower respiratory exchange ratios than men, which indicates more fat burning and less carb burning.
Women are better at converting ALA into DHA, and they also tend to have more DHA and AA circulating throughout their serum than men, who have more saturated and monounsaturated fat.
These differences in fat metabolism aren’t seen in isolated muscle cells of men and women, which isn’t really surprising. We’re made with the same basic building blocks; we just run on different software. The differences are systemic and hormonal.
Why does this sexual dimorphism in fat metabolism exist?
Well, the name of the game in evolution is reproduction, and reproduction is far more nutritionally expensive for women than it is for men. I don’t think I have to spell out why – for a man, the reproductive process is a brief moment in time, a half tablespoon’s worth of effort; for a woman, the reproductive process lasts the better part of a year and represents a significant drain on nutrient stores. As such, women are “designed” to hold onto said nutrients because, as far as evolutionary fitness is concerned, her primary purpose is to feed, nurture, and cultivate an entire other human being inside her body for nine months. Think about that for a second: women have to create and support another life inside their bodies. They have to provide the food, the water, and the shelter. If something goes terribly wrong in the “outside world,” that nutrient flow to the fetus could be interrupted, thus putting her evolutionary purpose at risk.
Now, imagine if the body didn’t know best. Imagine if the expectant mother had to know precisely what the fetus needed at any given moment – what precise nutrients were needed, which foods to eat and when to eat them in order to provide said nutrients, what to drink and how much of it, what not to eat nor drink – and then make a conscious decision to provide those things right on schedule? It wouldn’t work. We wouldn’t be here. Luckily, the body “knows.” The body will draw on what’s stored and what’s provided to make a health baby. And if it’s not all there, it’ll even convert other stuff into the stuff that it actually needs. Sure, a good diet will absolutely improve fetal health, but we’ve all known parents with less-than-ideal diets who have healthy kids. The body knows.
Which is why women store and burn fat differently than men. In order to be able to provide those nutrients to the growing child, female bodies store certain types of fat in certain places on the body. Female bodies “hoard” certain types of fat and are loathe to relinquish them “just cause you had a simple caloric deficit.” Whereas a man could go low carb Primal and lose weight pretty easily because all he “has” to be able to do is provide a bit of sperm, a woman’s body has more important things in mind, like having enough body fat on hand to produce enough leptin for optimal fertility, or enough DHA stored in lower body fat to build a robust baby brain.
How does this affect my recommendations or your diet, if at all?
Women – don’t be concerned about a little (or more than a little) subcutaneous body fat, especially on your lower body. If you’ve been trying in vain to lose that stubborn jiggle on your thigh, consider that maybe, just maybe it’s there for a reason. Even if you’re not interested in having a child, it’s likely that the presence of lower body fat indicates good health. You don’t have to get pregnant, but the ability to do so is probably a marker of good health, and the research outlined above suggests that classically feminine patterns of fat deposition are healthier than classically male patterns. And even if you don’t like your glutofemoral fat, rest assured that the males in your life (even ones as far away as Papua New Guinea – PDF) likely do!
Men – most of the fitness and health literature is geared toward you, so I’ll just suggest that you take this information on gender differences in fat metabolism into consideration.
I’ve always stressed the relativity of a person’s ideal body composition. I’ve discussed my own failings at trying to eat big and lift big to get big. I managed to put on five pounds of muscle by eating and working out way more than was comfortable or natural, but it made me lethargic, and as soon as I skipped a meal or workout, muscle would just peel off. That’s my comfortable body composition. Your ideal body composition might look very different, and, if you’re a woman, it might look very different from a man’s. That’s fine. That’s natural. That’s attractive. That’s how it’s supposed to be, and by trying to fight it – in either direction – your health may suffer.
What do you folks think about all this? Does this take a load off your mind, or does it open up new avenues of inquiry? Let me know in the comment section!
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Posted By: Mark Sisson
Damn. And I was hoping you were going to tell me exactly what to do to get rid of my outer thighs that seems to think they run my show…
I am adding my plea for more info on females who store fat on their abdomen. I have always had “runner legs” despite never running, and small arms. Fat accumulates aromd my waist first and then my breasts, and good luck ever getting rid of it. What could be causing this, how can we change it, and
And is it unhealthy or just our personal variation?
Thanks, Mark!
Great article, but you forgot a couple places where we store fat preferentially — I’ll give you a hint: they’re to do with lactation.
That’s another nice thing about primal compared to semi-starvation diets (i.e. low cal/low fat), is that with primal, body fat is preserved in all the right places!
for Jodie and Nikki, who mentioned they had trouble losing abdominal fat — what about trying a careful carb count for a few days and then experimenting with lower levels…
I know I need to keep carb counts closer to 20 than 50 to have visible abdominal muscles, while still maintaining fat in the right areas. [Overall I'm about 20% body fat, heading towards 19%].
The reason my carbs need to be so low is there is a genetic predisposition to obesity in my family. [But I think if you had many pounds to lose, you might also benefit from more carb restriction. Gary Taubes talks about that in "Why We Get Fat and What To Do About It". Jimmy Moore's been talking about it, too, over on his blog.]]
It’s a very different way of eating — usually by the time I’ve finished breakfast I’ve had about 1000 cal. of fat…. I eat about 3,000 cal a day, half of those at breakfast.
I do more low- and medium-intensity exercise now (started training for a triathalon with all the extra energy that eventually came with this shift in my diet, hence the 3,000 cal a day intake) but when I started last year it was just Doug McGuff’s 12 min per week “Body By Science” approach to exercise. That was enough to start changing my look and capabilities…and it also made a big difference in my fat burning, specifically off my abdomen.
Hope that’s helpful…
Thanks I will try that.
Interesting and informative post. Anyone else have “Baby’s Got Back” running through their head? LOL
I do think that things are a little different for peri and post menopausal women though. All the fluctuation in hormone levels definitely affect the fat distribution. Also, stress and cortisol levels play a huge part in where your fat is stored (IMO). I’d love to see the whole peri/post menopause issue addressed.
I feel better! Even with 8 months of nursing so far, the fat has been SLOW to come off. This article also hints that different women store fat differently. And gain muscle differently, as Mark points out with his own example. Focus on acceptance and HEALTH, rather than some body ideal, is key for me.
I dont think I have ever been so happy to have a big ass in my life! After just a month of primal I feel spectacular not just because i am not a slave to the 3 hr meal plans anymore but because of this… I am so at peace with my body and instincts. i used to eat low fat and after a few days go nuts and crave half n half. Gee i wonder? Its so nice to just make peace and realize we are that way for a reason…and still get a bit of a smaller butt in the mean time….Thank You Mark!!!!!
Great post Mark! Love the part about how the body “knows”
IMO the difference between the effects of subcutaneous fat and abdominal fat is fascinating and although it’s known they’re very different, we don’t hear about it way often enough!
It can be a problem in both directions — fit athletic people (esp women but not only) who needlessly worry about a little bit of subcutaneous fat on top of their muscles
–but also people whose BMIs and weights seem OK but who have abdominal fat. They and their doctors can underestimate their risk of diabetes and heart disease.
AFAIK measuring waist/hip ratio is a rough way to estimate
I really appreciated your comments about trying to eat big, workout big, to get big. I was much the same when I was younger. Always wanted to be bigger. I tried for 6 months to put on weight with lots of extra calories and too much weight lifting and managed to gain ~7lbs. I was ripped though. However like you, a few weeks of slacking off due to burnout and the weight was gone. Much happier now to weigh less but have a lean, easier to maintain physique.
Still doesn’t explain why some of us women cannot attain that attractive athletic body on this diet no matter what we do.
I’m glad this article was posted–was JUST talking about this with a friend. Sometimes it’s frustrating for us women, because we’re involved in a community where men generally seem to have greater/faster success than we do (in terms of fat loss). And yet I still have to endure hearing the “You can eat as much paleo food as you want and LOSE weight!” Not sure who came up with that line of thinking, but it sure isn’t true for someone like me.
These last ten pounds on my frame are holding on for dear life! That all being said, I def feel better and leaner following this way of life, and I encourage curious friends and family to give it a whirl–better health equals a better life. I’m super glad I made the switch from vegetarian to primal
Adding another voice here to the requests for post-menopausal women and fat/weight loss/body composition. And maybe the latest and greatest research on estrogen supplementation in those early years of menopause – I’ve been researching this on my own but, Mark, you do it so much better!
It would be great if this kind of knowledge were published in magazines/on blogs that teenage girls and young women read. They might be encouraged to not worry about their body image so much.
Thanks for pointing out the differences, Mark. I’m another post-menopausal apple shape that can’t seem to budge the weight. I was doing fine until the hormones changed direction! I don’t know that there’s any natural way around that.
I was expecting this article to say a lot more about testosterone in relation to fat metabolism. My understanding is that the differences between male and female metabolism are largely attributable to differences in hormone levels.
The reason men on paleo can obtain a lean, muscular build while female role models on paleo are often plumper is that testosterone helps metabolize fat.
So, if a woman wanted to reduce that fat to a healthy but lower level, would we talk about lowering the fat overall by not adding fat, increase protein to 40-50%, and choosing O3 eggs, wild salmon and g-g beef over the pork, poultry in skin and nuts/avocado. Prefer coconut oil over every other fat source. Avoid high sugar foods? Add 20 min steady state cardio after each lifting workout? What?
The way I’m understanding it is more that what’s a healthy level of body fat for the average woman is higher than what’s a healthy level of body fat for the average man.
I.e., you may not look like a TV model but if you have strong muscles, good energy and endurance,
feel good, and your body fat is mainly subcutaneous fat as described in the article (i.e., hourglass shape or pear shape), you may actually be healthier than that TV model.
Mark’s Body Fat % is lower than an average male’s BF%, and nobody is going to argue that he is healthy. So, if a woman wanted to achieve the same, healthy but below average BF%, what are the recommendations? Not a model with no muscle and 15% BF, but a fit woman with 16-18% BF and large muscle size instead of pudgy average woman at 25% BF.
25% body fat isn’t pudgy for a woman, and I’m certain it’s not average. It may be a little higher than athletic ideal, but it’s still reasonably good.
No, just the opposite.
I’m trying to build muscle and get a bit leaner lately and it’s been difficult with the available shelter/soup kitchen food. I’ll pig out on stuff like cheap cheese and cereal or other high-carb foods (french fries for ex., even some bread/bagels) and end up bloated and gaining noticeable fat fast, then if I cut back I’ll lose the fat fairly fast but also lose muscle. A few years ago my body probably looked better than now overall, and I was probably in better shape. I recovered a lot faster from workouts too – maybe because I was conditioned to a routine, maybe there was less strain on my system. After 5 years of reckless drug usage I’ve only been off them for about three weeks now – I’m guessing there’s all sorts of healing and cleansing that has to happen before my organs put their resources towards building and maintaining muscle, though ironically I think I have a fairly normal countenance and skin tone, whereas a few years back I was fairly “ripped” at times and had quite a bit of energy but my face looked like that of an addict and my skin tone was kind of patchy. I think I should get a bike. I used to bike everywhere and it was a great thing.
A couple months ago I was getting abs but unstable circumstances + a dumb diet mess with my body composition constantly, so I guess they’re still mostly there, but not visible. A recent back injury limits my exercise so I’m kind of confined to hiking and a little easy-going tree climbing, some chin-ups and monkey bar sit-ups.. jogging hurts and even push-ups kill my lower back after a bit. I’m finding it difficult to burn sufficient calories by exercise so now I’m toying around with caloric restriction, eating lots of veggies and protein (with some animal fat) to see how that goes, while drinking quite a bit of coffee in the morning and tea the rest of the day, a small amount of molasses here and there for minerals. I’m basically trying to shock myself into ketosis. The huge bowls of rice crispies must go! I feel sore and hungry but kind of good.
Later on that evening just kind of thought, “forget that”.. went out and did pull-ups and a bunch of curls with a log. Stuffed myself with mostly healthy food, lots and lots of mixed greens, that really helps with satiety.
Going for more micronutrients and trying not to worry about calories. If I work hard enough, they’ll burn.
*Applause* Thank you, Mark. Well written!
Not sure if it was mentioned above but this post is only correct for younger people. As people age, the fat distribution pattern on their body changes. Not sure if any one has noticed that women approaching and past menopause often lose the extra fat on their *sses and thighs and start to accumulate more on the upper body – primarily the abdomen. You often see ladies in their 50-60′s with tiny butts. In men, as they pass middle age, their fat stores on the abdomen often shift downward onto the hips and legs.
This may be primarily a result of changing sex hormones. As women age they usually produce less estrogen and more testosterone. In men it is the reverse. This affects emotions as well – older men can be maudlin and older women often become more assertive.
This process does not happen at the same rate or even in everyone – it may depend on diet, genes, activity etc.
But is certainly is prevelant in America.
Cheers
j
Oh and further to my comment above – don’t forget, womens breasts typically shrink past a certain age and men grow them.
For younger women who have apple shapes – likely a hormonal factor at play – likley could be changed somewhat though diet and exercise and reducing stress levels.
Wow, thanks Mark! Judging from the comments of all your primal “girl friends” out there, I think more posts like this are needed.
Well, I just turned 60 and I don’t have a tiny butt.
I do agree that fat deposition may change a little. For instance, fat more across the back and arms for some women.
I have my own ideas (and some will agree with me) about what happens to fat stores around the time of menopause. Women’s ovaries sure aren’t providing anything post-menopause, so where does the estrogen come from? From where it’s stored in the subcutaneous fat, naturally. I think this extra fat is needed transitionally to get through menopause.
However, yes, in my experience, there comes a time, several years past menopause when the female body, indeed, is “ready” to give up more stored fat. Sure was true for me. At 5’4″, I now weigh 120. I haven’t been that lean since 1994. It’s only my experience, however. I have lucky genes and no diabetes nor much obesity in my family.
Interesting thoughts, Erin – and a little encouraging for me. I’m just starting down the back side of menopause and the subcutaneous just does not want to leave – even the extra I put on during the 10 years prior to menopause. Maybe I just have to be patient for a couple of years and keep up with the primal lifestyle.
Lynn,so true, thanks! I heard that from a health professional, but also from my grandmother and great grandmother,(both lean,french farmer centenarians – old wive’s tales,hehe) that a woman should have an extra few pounds, if she was lean, to get her through menopause. I am like you,small and 105, went down to 100 around peri, then gained to 110, all primal (+ a bit of cheese) to get me through it, with no additional problems. Now back to 103-4 as usual, all muscle but small gluteo-femoral curves, that fall off if I swim more regularly(good for back and arms too.) (Also important is the inherited proportional hip/waist/shoulder ratios.) You mentioned subcutaneous fat estrogen, and estrogen is stored in fat cells, so there you have it! Good luck!
What if you’e an androgen insensitive xy? Lol kidding. Seriously, im a skinny legged um Grrrl, with NBAA syndrome, NO BUTT AT ALL? Im starting to wonder about my lack of omega 3s?
Great information today. However, I would add my vote for more information about post-menopausal women’s differences and issues. There are a lot of us here in primal-land. Appreciate all you do for us.
There are also age differences in where people store fat: postmenopausal women typically store a little more abdominal fat. This abdominal fat makes estrogen for you, since your ovaries have slowed down estrogen production. If you lose that abdominal fat entirely, your libido may plummet.
Great article, this highlights a good point, that women need to be comfortable with their healthy bodies even when we have a little bit of jiggle left! For me losing weight after my third baby, my upper half has thinned out quickly while my hips butt and thighs take much much longer, and truthfully after three kids not all of it may ever be gone…and I am cool with that! Health is more important….that extra jiggle in my walk is a badge of honor!! I created three little lives….ain’t nothing more Primal than that!!
Well, i”ll represent the minority/devil’s advocate…
Er. As I was saying…
Articles like this one and the “intermittent fasting for women” one actually make me feel a little LESS hopeful. If the societal ideal is to be lean – not to mention the primal/paleo ideal – then we ladies are kind of up poop’s creek it would seem.
For 2 years I’ve been eating grass-fed meat, lifting heavy tings, sprinting, going for long slow walks – doing all of the things that are touted as the makers of the lean bodies by the paleosphere: “Not losing fat? Try sprinting!” “Hit a weight loss plateau? Walk slowly for 5+ hours a week!” “Want to ramp up the leaness? Skip breakfast!”
And then it all boils down to “Actually, you’re a chick, so nevermind.”
All this means is I need an attitude adjustment, really. But I thought I’d throw it out there in case any other ladies were left feeling a little hopeless in amongst all the “Yay! My thighs are a sign of good health!”
With the utmost respect for my sistahs who are comfy in their not-super-lean bodies (and wishing I could be cheering for my thighs right about now),
Erin
yeh, Erin, I’m kinda with you…I will NEVER look good naked. not after creating 5 kids. my body is slim-ish and healthy, but my belly is disgusting! primal or not, having children creates lives and destroys the mother’s body.
If you have 5 kids, seems to me that someone thinks you look pretty good naked!
I know it’s unhelpful sometimes to hear it from men because women compare themselves to women, but men enjoy women’s bodies in all shapes and sizes.
When we don’t point our our “imperfections” to the men in our lives they probably don’t even notice them.
That said, I don’t appreciate my body nearly as much as my husband does. (He thinks it’s perfect and I still think it needs work.)
I will say this: after a couple of years of Paleo/Primal eating, I have noticed my body composition has changed. My waist to hip ratio used to be 4-5 inches. Now it’s 10. And I don’t weigh that much less. I am just storing fat differently. It used to all be in my stomach and waist- I was like a potato on stilts. Now I have a serious hourglass. My pants are a size smaller- bigger in the waist, smaller in the butt and thighs than they used to be. Yes, I’d like to lose weight, but losing weight doesn’t necessarily mean gaining health- unfortunately, we are conditioned to believe that.
I get what you are saying. At least I think I do.
I’m someone with squishy thighs who can get to 12-15% bf with a lot of discipline and desire following a body builder style diet. With a lot of desire is key. I no longer have that desire. What I find really surprising is all the “wow” “great post” comments. It’s well written but my goodnes I thought every woman would know this by now. Women carrying more far and having a harder time losing than men because they are the baby growers. And fat on the hips/but/thighs is a sign of health. It’s sort of “no shit sherlock”. What I find depressing is the amount of women this is apparently new information too. Sigh.
It’s not so much that it’s new information as that it seems to be acknowledged relatively infrequently, particularly any time people are talking about weight loss, or about appearance. It gets frustrating hearing and reading all these things about how to ‘lose those last ten pounds’, get visible ab definition and so on, as if that’s an obviously good thing (some women do look like that when healthy but for many it’s a sign of being underweight). So it’s nice to see it pointed out clearly now and then, in an article that focuses on how to be HEALTHY.
Thank you, Erin!
Interesting article. It would be very exciting to dive into a comparative physiology expose on the difference between cohorts for fat metabolism. Like gender, age groups, nationalities and so forth…that is too big a job for me however…
Thank you for making me feel better about my huge, un-lose-able ass.
Great post and it does relieve my mind as I have always been one of those whose body type has screamed good metabolic health.
However, I’m now passed the child-bearing years – did any of your research indicate a difference for women after menopause? I’ve been maintaining a primal diet for a year now and about 3 months ago the weight stopped coming off despite still being 40 pounds above what I think is optimal for me.