Weight Gain in Menopause

By Paul Hueseman, PharmD
July 2006

brought to you by Bellevue Pharmacy, a ProjectAWARE sponsor

Many women are concerned about weight gain that is typically associated with menopause. Although the average woman gains two to five pounds during the menopausal transition, some women are at risk for greater weight gains. There is also a hormonally driven shift in body fat distribution to midsection fat stores in menopause.

Women's weight gain and increase in adiposity (fat) in mid-life are thought to occur through a number of mechanisms. Almost all the available long-term studies of the perimenopausal transition show that natural menopause does not affect body mass index (BMI) or cause weight gain. So are women gaining weight or not? And what impact does estrogen replacement have on the process?

Few reported studies have had a sufficiently long period of observation to show that weight gain actually does occur as a result of menopause. For this reason the issue of what happens to body weight at the menopausal transition itself has remained unclear. The longest available study evaluated women over a 20-year period and found on average women gain total body weight from age 35 to 65 and that neither the loss of ovarian hormones nor their subsequent replacement reduces a detectable change in this trend.

While estrogen replacement has not been found to impact weight gain, other studies have found that it helps manage abdominal fat stores better than women not taking estrogen replacement. This points to estradiol, which decreases in menopause being responsible for fat redistribution to the abdomen.

How exactly does estradiol regulate the fat distribution? Factors controlling human adipose tissue accumulation/metabolism are largely unknown. What is known is that low estrogen levels that occur with menopause are associated with loss of subcutaneous fat and gain of visceral fat. Visceral fat is located around organs inside the abdomen and deeper in the body than subcutaneous fat. The fat cells around the abdomen are regulated by estradiol, whereas the fat cells in subcutaneous tissue are not. As women approach menopause, their estradiol levels decrease. They then no longer have protection from abdominal weight gain. Since the two different types of fat cells are now on equal metabolism levels, fat is then allowed to accumulate in the abdomen.

The most difficult concept to grasp is the clinical question Do higher levels of estrogens cause obesity, or does obesity cause higher levels of estrogens? Since higher levels of estrogens are seen in the heavier postmenopoausal women, clinicans have been led to believe that these higher estrogen levels have caused the obesity, which is not the case.

First, weight gain, especially in the abdominal region, causes insulin resistance and subsequent increases in plasma insulin and insulin growth factor (IGF-1), which leads to increasing levels of estrogens and bioavailable androgens, testosterone and androstenedione. This excess weight results in increased estrogen concentrations from conversion of androgens, mainly androstenedione, to estrogens, mainly estrone. After menopause, when ovarian production of estrogens stops, this conversion becomes the primary source of estradiol.

In addition to prevention of abdominal obesity, estrogen replacement therapy has been shown to prevent subsequent progressive insulin resistance consistent with metabolic syndrome and reduce the risk of developing diabetes.

Weight gain does happen in menopause, but that's not to say that it happens because of menopause. Weight gain is generally always happening as people age. All too often the weight gain is blamed on menopause. This may be easy to do, however, because the central obesity fat mass transition is noticeable. In reality, the woman may weigh the same as a few years ago, but the pants may not fit comfortably anymore.

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