It is common for women to gain weight during mid-life, and it’s often blamed on hormonal changes related to perimenopause, menopause or treatment for those changes (i.e. hormone therapy). Let’s examine the facts.

Changes as a result of declining levels of estrogen and progesterone

Changes usually start between the ages of 45-55. Ovaries slow egg production and eventually stop. As a result, the ovaries produce less estrogen and progesterone. Menstrual cycles start to change, and menopause-related symptoms may appear (hot flashes, night sweats, etc.).

Is weight gain a side effect? What does the scientific research tell us?

Much research has been done on this topic. Studies have looked at: women of the same age but in different stages of menopause; the rate of weight change in connection with menopausal status and hormonal changes; and ethnic variances. SWAN (Study of Women’s Health Across the Nation) conducted a large weight survey with 16,000 participants. No difference in BMI was found between premenopausal and post-menopausal women after age and other variables were adjusted for. SWAN did another study with a smaller group of women who were divided by ethnicity. The median weight of the women in the study did not differ by menopausal status. The average weight gain over the 3 year study was 4.5 pounds and was determined to be unrelated to menopausal status. The evidence shows that weight gain during this time is not a result of the hormonal changes.

If it’s not the hormones, why is it so much harder to lose weight or even maintain it?

Though these mid-life hormonal changes do not cause weight gain, there are factors that can contribute to weight gain.

• Changes in fat accumulation

Scientific evidence shows that estrogen depletion can cause a change in the distribution of body fat. Fat accumulation shifts to the abdominal area (even if a woman previously carried body fat mostly in her hips and thighs), which can change her overall shape and appearance. Much of that fat seems to be visceral fat, which is stored internally in the abdomen around the organs. Though hormonal fluctuations during perimenopause/menopause do change WHERE fat is accumulated, they do not cause fat mass to be gained. It still takes a 3500 calorie surplus to gain a pound of fat.

• Changes in Energy Levels

Night sweats can cause sleep disruptions, leaving you feeling tired, irritable and less energetic. This can make it less likely that you will exercise. When you exercise, decreased energy can affect the intensity level thus decreasing the calories expended.

• Changes in Activity Levels

Women generally become less physically active during their 40s and beyond. This change is due to lifestyle changes, such as the demands of work, kids, etc., replacing or taking priority over physical activity. At any age, burning fewer calories from being less active and not changing caloric intake increases weight and fat mass.

• Changes as a Result of Aging

• Decreased lean mass (as you lose muscle your metabolic rate will slow). This happens as we age typically at a rate of 1-2% per decade, but it is largely due to decreased activity levels.
• Decreased aerobic capacity. This declines 5-15% per decade starting at age 25. Decreased aerobic capacity means you have to increase the amount of time spent to expend the same number of calories as you did 10 years ago. The lower your activity levels, the greater the decrease.
• Decreased caloric needs as a result of decreased activity levels.

Is increased fat in the abdominal area equivalent to fat in other areas?

No! Abdominal obesity (waist circumference 35 inches or greater for women) is associated with increased risk for heart disease, insulin resistance and type 2 diabetes.

What if I’m on hormone therapy?

Studies show that hormone replacement therapy is not associated with weight gain OR increased abdominal fat. In fact, it may prevent the abdominal fat accumulation associated with estrogen depletion. Studies have mostly shown a reduction in overall body fat, improved insulin sensitivity and lower rates of type 2 diabetes.

Does obesity or weight gain alter perimenopause/menopause?

It is well established that obesity may be associated with changes in menstrual cycle length and hormone patterns. During the menopausal transition, symptoms increase as weight increases, and obesity is a risk factor for more severe symptoms. Reductions in weight and waist circumference have been associated with decreased symptoms.

Conclusion

“There is no scientific evidence that menopause or hormone therapy is responsible for midlife weight gain.” North American Menopause Society

Studies have consistently shown that lifestyle and age, not menopause, are the main factors in mid-life weight gain. Hormonal changes, however, do affect the patterns of fat distribution, causing greater accumulation in the abdominal area. Decreased energy needs along with decreased energy expenditure make it necessary to monitor intake and keep exercising to maintain or improve body composition. What is the best thing to do to prevent middle age weight gain? Monitor calorie intake (and make reductions if needed), exercise, and include resistance training to preserve lean mass.