Greater weight increases the likelihood of night sweats and hot flashes during early stages of the menopause transition but reduces those symptoms throughout menopause and beyond, new UC Davis research published in the journal "Menopause" shows.
The study clarifies mixed results from previous research indicating that higher weight was both a prevention and potential cause of hot flashes and night sweats, also known as vasomotor symptoms, which affect up to 80 percent of menopausal women and are a major reason for doctors' office visits.
"The relationship between weight and these symptoms differs depending on the timing," said lead author Ellen Gold, a UC Davis professor of public health sciences and women's health researcher.
"It's possible that the greater heat insulation provided by excess weight predisposes women to these symptoms early in the menopause transition, when the ovaries are still producing estrogen and women are still menstruating," Gold said. "Higher estrogen production that occurs with higher body fat plays a more influential role and becomes protective later -- after the final menstrual period and when estrogen production by the ovaries is greatly reduced."
In conducting the study, Gold and her colleagues used data from the Study of Women's Health Across the Nation, or SWAN, a longitudinal, multicenter study of more than 3,000 women aged 42 to 52 years from five racial/ethnic groups.
During annual visits over the course of 10 years, participants were measured for body mass index (BMI) and responded to questions about their experiences with frequently occurring menopausal symptoms. Those undergoing treatments that could trigger or reduce vasomotor symptoms were excluded.
The longitudinal results showed that being obese, or having a BMI greater than 30, was significantly related to increased occurrence of vasomotor symptoms in the premenopausal or early perimenopausal stage, when women were still menstruating but periods may have started to become somewhat irregular. Being obese, however, was negatively associated with these symptoms during later stages of menopause, when periods were 3 to 11 months apart or had ceased. Changes in weight during either stage did not alter the outcomes.
The results suggest that maintaining a healthy weight just prior to and at the onset of the menopause transition could be helpful for reducing hot flashes and night sweats, but some excess weight late in the transition or after the final menstrual period may be protective.
While the study benefited from a large, diverse study sample, Gold said that much still needs to be learned about these frequent menopause symptoms.
"We really need additional research on the underlying biologic mechanisms by which weight and women's circulating hormone levels interact to help us develop safe and effective preventive strategies for hot flashes and night sweats," Gold said.
Gold's co-authors were Sybil Crawford of the University of Massachusetts; Janie Shelton of UC Davis; Ping Tepper, Karen Matthews and Rebecca Thurston of the University of Pittsburgh; Carolyn Crandall and Gail Greendale of UCLA; and senior author Nancy Avis of Wake Forest University.
Their study, "Longitudinal Analysis of Changes in Weight and Waist Circumference in Relation to Incident Vasomotor Symptoms: the Study of Women's Health Across the Nation (SWAN), is available online in the journal's "Ahead of Print" section.
SWAN is supported by the National Institutes of Health through grant numbers U01NR004061, U01AG012505, U01AG012535, U01AG012531, U01AG012539, U01AG012546, U01AG012553, U01AG012554 and U01AG012495.
More information about UC Davis Health System and its Department of Public Health Sciences is at healthsystem.ucdavis.edu.