6 Surefire Ways to Stay Slim After 35
The Estrogen Effect
In women over 40, however, that equilibrium begins to falter, says Dr. Lark. Estrogen is usually believed to drop off in midlife, but actually levels fluctuate, alternating between steep declines and sharp increases during perimenopause (the two- to eight-year period leading up to menopause). Yet even before their periods become irregular, perimenopausal women have cycles in which they do not ovulate. During these anovulatory cycles, there is a drop in progesterone. Thus, the balance between the two hormones is thrown out of kilter -- unfortunately in favor of fat storage.
Adding insult to injury, estrogen contributes to fluid retention, which means that during low-progesterone cycles it's not uncommon to carry around an extra two to five pounds of water weight, according to Dr. Lark. This goes away during normal cycles, but the number of anovulatory cycles increases with age. That means water weight sticks around longer and can be mistaken for fat.
Naturally, given the infinite wisdom of Mother Nature, there's a good biological reason for this fat-amassing propensity. Since estrogen is produced in fat cells as well as in the ovaries, the accumulation of fat during perimenopause may be nature's way of compensating for the oncoming loss of estrogen during menopause itself.
But estrogen is not solely to blame: The ovaries also produce testosterone, and fluctuations in this hormone before menopause can affect energy levels. So you're apt to exercise less, which leads to a reduction in lean muscle mass and a tendency to conserve fat. (Muscles burn calories even at rest.) In addition, a midlife decrease in the output of growth hormones slows the metabolism by about two percent a year, beginning at around 40, says Michael Goodman, MD, author of The Midlife Bible: A Woman's Survival Guide. "Basically, your motor is idling at a lower speed," he explains. "This change decreases calorie expenditure by as many as 25 to 100 calories a day -- even if you're exercising and eating the way you always have." (If it's any consolation, men in midlife, though spared the hormonal roller coaster, are equally subject to metabolic slowdown -- and many have the spare tires to prove it.)
But another harsh truth is that you may not be eating and exercising the way you always have, even if you think you are. Besides dealing a blow to your energy, hormone fluctuations can increase stress-related eating, says Dr. Peeke. Women of all ages produce 50 percent less serotonin -- the hormone linked to feelings of well-being -- than men. Thus, at times of stress, such as during PMS, they are more likely than men to boost their serotonin levels by eating sweets, particularly chocolate. Because the duration of PMS often increases during perimenopause, perimenopausal women are more likely to crave sweets, says Dr. Peeke. And extra chocolate carries extra calories.