By Kristen Fischer
Hot flashes can be debilitating for more than 50 percent of menopausal women, said Dr. Taraneh Shirazian, an assistant professor of obstetrics, gynecology and reproductive science at the Icahn School of Medicine at Mount Sinai Hospital in New York City. About one-third of menopausal women experience more than 10 hot flashes a day, and she added that hot flashes are more common in obese women.
"Fat appears to function as an insulator, and interferes with heat dissipation," explained Shirazian, who was not involved in the study.
Rabin said she has found that obese and overweight women have, in general, more severe and more frequent hot flash symptoms.
"They have a harder time with the menopausal transition," she said. "It may be the extra fat that makes heat dissipation more difficult."
Overweight and obese women may also yo-yo diet, which could mean they have fluctuating estrogen levels, and that could make it harder for their bodies to regulate their internal temperatures, Rabin added.
In the new study, published online recently in the journal Menopause, Rebecca Thurston of the University of Pittsburgh and colleagues followed 40 overweight and obese white and black women who experienced hot flashes during menopause. They divided the women into two groups: One group went through a weight-loss program for six months, while the other group (the "control" group) was told they were on a wait-list for a clinical study.
Using physiologic monitoring, diaries and questionnaires, the investigators measured details about hot flashes as they occurred in women who had four or more hot flashes a day. The women were either in the later stages of perimenopause (not having menstrual periods for three months to a year) or postmenopausal (not having a period for a year or more).
The researchers found that three-quarters of the women said easing hot flashes was a huge motivator to shed pounds. The women in the weight-loss program group lost, on average, 10.7 percent of their weight and 4.7 percent of their body fat throughout the study period. There was almost no change in either weight or body fat among the women in the control group. Of the 33 women who completed the study, those in the weight-loss group had a greater reduction in hot flash incidents.
The researchers noted that the findings need to be confirmed in a larger study.
Dr. Robert Taylor, a professor of obstetrics and gynecology at Wake Forest Baptist Medical Center in Winston-Salem, N.C., said he found it interesting that the women who saw the most significant reduction in symptoms were closest to their final menstrual period, while those further along in menopause saw a less pronounced effect.
During perimenopause, a woman's ovaries still produce estradiol, a potent form of estrogen that can ease hot flashes, he explained. Estrone, another type of estrogen that comes from fat, actually counteracts estradiol's effects.
"With weight loss, production of estrone decreases, so circulating estradiol is more effective," Taylor said, and this is why overweight women may have more severe symptoms than women who are thinner.