I have been receiving a fair number of e-mails and messages about the Gender Differences in Fat Deposition post over at Mark Sisson’s site. Can I throw my hands up and say “ah ha! We did it! The giants are talking about sex differences. Now I can retire and move on to different projects”? Yeah, maybe a little bit. But I won’t. I’ve become too addicted to this community and work. Which, of course, needs all of the advocates and passion we can throw at it.
Anyway, briefly. I addressed the physiology of women’s weight loss in two posts: The Physiology of Women’s Weight Loss Part I: Estrogen, and The Physiology of Women’s Weight Loss Part II: Appetite and Weight Regulation. I go into a fair bit more depth on both of those topics than Mark does, though he also points out a few great differences:
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 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.
Mark also remarks in his post, much like I did in my estrogen post, that women tend to store fat around the hips buttocks and thighs, and this has been shown time and time again to be healthier than the typical male pattern of abdominal fat deposition. This is well known in the literature and encouraging for curvy women everywhere.
I have, however, been getting a lot of questions about fat deposition in the abdomen. When and why do women still store fat in their abdomens, even though they traditionally have more subcutaneous fat than men?
1) Women store fat in the abdomen during menopause.
Women store fat in their abdomens during menopause fairly frequently. This is because estrogen levels are dropping sharply. Many women supplement with bio-identical hormones, in fact, and see their weight gain / weight shift minimize. Another great way to mitigate this problem is to eat a diet consisting of whole foods, which will minimize insulin spiking that can also contribute to abdominal fat gain, and which will also keep hormone levels fairly well-balanced.
Menopausal women may also want to play around with soy if they are experiencing dramatic menopause symptoms. Please proceed with caution in that case, however. I wrote about how complicated soy is here.
2) Women store fat in the abdomen when they are stressed out.
Cortisol drives abdominal fat deposition. This comes from stress as well as from any loss of sleep quality that may have occurred as a result of stress.
Cortisol and insulin tend to run together, as well, which means that this point and the following point can be difficult to untangle.
3) Women store fat in the abdomen when they are insulin resistant.
Insulin resistant women experience more abdominal fat deposition than those who are insulin sensitive. Moreover, a woman at any single BMI can be insulin resistant, which means that thin women can have IR problems still and deposit fat in their abdomens. The results from one study are particularly striking:
” We found a strong negative relationship between central abdominal fat and whole-body insulin sensitivity, and nonoxidative glucose disposal, independent of total adiposity, family history of NIDDM, and past gestational diabetes. There was a large variation in insulin sensitivity, with a similar variation in central fat, even in those whose BMI was <25 kg/m2.”
IE: Insulin sensitivity in both overweight and normal weight women drives abdominal fat deposition.
4) Women store fat in the abdomen when they are particularly genetically primed to.
Some women naturally have more fat in their abdomens than other women do– that’s just how genetic rolls the dice. It’s okay, it really is. It does not mean you are unhealthy. Only blood tests might reveal that. Each woman has a different shape particular to her genetics and her history.
Have experiences with different kinds of fat? Fed up with hefty ab fat but non-existent ass-fat like Elissa? Have a hard time loving your stomach even though you totally should? Let me hear it in the comments!