Menopause and body fat

Menopause and body fat

Our bodies are constantly changing—sometimes for the better and other times for the worse. Because of the unique role a woman’s body plays in fertility, namely growing and later feeding a new human, it’s little surprise that her body undergoes more pronounced changes throughout life compared with a man’s. One of these obvious changes is the storage of fat, the most obvious sign of metabolic health. Metabolic and reproductive functions are intimately linked; reproduction won’t happen if the metabolic system is in disarray. 

The Beginning and the End: Puberty and Menopause

Puberty and menopause represent the beginning and end of reproductive years. Beyond the reproductive alterations, both of these periods are evident in meaningful physical changes. In both instances, whether at the beginning or at the end, alterations in hormones dictate the changes in the body. And while these hormone changes are obviously relevant to reproduction, some of the hormone changes also affect body fat. 

Sex Hormones and Body Fat

Sex hormones, which we divide into two general categories of estrogens and androgens, have numerous effects throughout the body. Other than the obvious effects of controlling reproduction, sex hormones have a powerful effect on fat storage. Specifically, they tell the body where to store fat, but insulin tells the body how much fat to store. In females, fat is primarily stored on hips and buttocks, and estrogens direct this process. However, this doesn’t mean estrogens promote fat storage—in other words, high estrogen does not mean high fat storage. In fact, quite the opposite is true—estrogens actually help keep fat storage at reasonable levels [1]. And this is where menopause comes in. 

Menopause is a fascinating example of how intimately the metabolic and reproductive processes are linked—when one is altered, the other usually follows. In this case, when estrogens plummet, a woman’s body loses two of estrogens’ beneficial effects on fat. 

First, with a reduction in estrogens comes a shift in where the body stores fat. Rather than signaling fat to store on the hip and buttocks, the fat moves up, being stored more readily around the stomach and center of the body. Overall, the fat storage pattern begins to more closely reflect what’s seen in men, who naturally have lower estrogens compared with women. 

Second, the estrogen drop means the body loses some protection against storing too much fat. This point is worth exploring, because it’s so misunderstood. In animal and human studies, we’ve learned that when you remove the ovaries (the main estrogen producer) or otherwise block estrogens from working, body fat climbs quickly, even when calorie number is the same [2]. 

One important idea to remember is that estrogens don’t make the body store fat, they only tell the body where to store fat. However, some of estrogens effects on preventing too much fat gain are related to the hormones that does, in fact, signal fat growth: insulin. Estrogens generally help the body be more insulin sensitive, keeping insulin levels lower [3]. The lower insulin, in turn, can accelerate metabolic rate and stimulate greater fat burning (i.e., “lipolysis”) [4]. Of course, menopause, with the loss of estrogens, means a loss of estrogens’ insulin-sensitizing actions; so, estrogens go down, and insulin levels go up. Altogether, these two changes explain much of the frustrations with body weight changes in menopause—weight gain in new (and unwanted) places on the body. 

Hormone-replacement Therapy

If losing estrogens during menopause is the source of metabolic problems, then restoring the estrogens with hormone replacement therapy (HRT) should solve it, right? Yep—it works. By replacing the estrogens lost from menopause, women will often improve insulin sensitivity and prevent the unwelcomed body fat changes [5]. However, lest this be viewed as an endorsement for HRT, there are other non-metabolic considerations to HRT. Estrogens’ non-metabolic effects including stimulating growth of reproductive tissues, like breast tissue and the uterus, which may increase the risk of cancers [6]. 

“Dietary Therapy”

While the changes in estrogens with menopause are inevitable, weight gain is not. As mentioned earlier, the hormone insulin largely controls the amount of fat we store while sex hormones determine where we store it. Thus, it’s no surprise that a diet that lowers insulin can help a woman in menopause lose weight better than a diet that does not focus on lowering insulin. Of course, when it comes to insulin, carbohydrates are the biggest offender. A study that followed post-menopausal women for six months placed the women into two groups differing in carbohydrate content: a low-fat diet vs. a low-carbohydrate diet. After the six months, the women in the low-carbohydrate diet had lost more than twice the weight of the women in the low-fat group [7].

Take-away Thoughts

Going through menopause brings uncontrollable reductions in estrogens that tend to increase fat gain around the stomach. Replacing those estrogens with HRT might be a solution for the metabolic concerns, but these need to be balanced with concerns beyond the metabolic. Do your best to control insulin (e.g., control carbs, prioritize protein, don’t fear fat) and you’ll be confident you’re doing what you can to soften the blow of losing estrogens. 

References

1 Tagliaferri, C., Salles, J., Landrier, J. F., Giraudet, C., Patrac, V., Lebecque, P., Davicco, M. J., Chanet, A., Pouyet, C., Dhaussy, A., Huertas, A., Boirie, Y., Wittrant, Y., Coxam, V. and Walrand, S. (2015) Increased body fat mass and tissue lipotoxicity associated with ovariectomy or high-fat diet differentially affects bone and skeletal muscle metabolism in rats. Eur J Nutr. 54, 1139-1149
2 Hong, J., Stubbins, R. E., Smith, R. R., Harvey, A. E. and Nunez, N. P. (2009) Differential susceptibility to obesity between male, female and ovariectomized female mice. Nutr J. 8, 11
3 Walton, C., Godsland, I. F., Proudler, A. J., Wynn, V. and Stevenson, J. C. (1993) The effects of the menopause on insulin sensitivity, secretion and elimination in non-obese, healthy women. European journal of clinical investigation. 23, 466-473
4 Ebbeling, C. B., Feldman, H. A., Klein, G. L., Wong, J. M. W., Bielak, L., Steltz, S. K., Luoto, P. K., Wolfe, R. R., Wong, W. W. and Ludwig, D. S. (2018) Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. BMJ. 363, k4583
5 Chmouliovsky, L., Habicht, F., James, R. W., Lehmann, T., Campana, A. and Golay, A. (1999) Beneficial effect of hormone replacement therapy on weight loss in obese menopausal women. Maturitas. 32, 147-153
6 Gray, S. (2003) Breast cancer and hormone-replacement therapy: the Million Women Study. Lancet. 362, 1332; author reply 1332
7 Lean, M. E., Han, T. S., Prvan, T., Richmond, P. R. and Avenell, A. (1997) Weight loss with high and low carbohydrate 1200 kcal diets in free living women. European journal of clinical nutrition. 51, 243-248