Weight loss that occurs in conjunction with a low-fat, high fruit and vegetable diet may help to reduce or eliminate hot flashes and night sweats associated with menopause, according to a Kaiser Permanente Division of Research study that appears in the current issue of Menopause.

This Women's Health Initiative study of 17,473 women found that women on a diet low in fat and high in whole grains, fruit and vegetables, who had menopausal symptoms, who were not taking hormone replacement therapy, and who lost weight (10 or more pounds or 10 or more percent of their baseline body weight), were more likely to reduce or eliminate hot flashes and night sweats after one year, compared to those in a control group who maintained their weight.

Many women experience hot flashes at some point before or after menopause, when their estrogen levels are declining, explain the researchers.

"While the mechanism is not completely understood, hot flashes and night sweats are thought to be caused by a complex interaction that involves fluctuating hormone levels, the hypothalamus region of the brain that regulates body temperature, brain chemicals and receptors, and the body's blood vessels and sweat glands," said Candyce Kroenke, ScD, MPH, a research scientist with the Kaiser Permanente Northern California Division of Research and lead author of the study.

Although previous research has shown that high body weight and weight gain are associated with hot flashes and night sweats associated with menopause, this study is the among the first -- and the largest to date -- to analyze whether weight loss on a diet designed to reduce fat and increase whole grains, fruit and vegetable intake might ameliorate symptoms. It is also among the first to examine the influence of a dietary change on symptoms that include hot flashes and night sweats, said Kroenke.

"Since most women tend to gain weight with age, weight loss or weight gain prevention may offer a viable strategy to help eliminate hot flashes and night sweats associated with menopause," said Bette Caan, DrPH, a research scientist with the Kaiser Permanente Northern California Division of Research and the senior author of the study.

She explained that greater body fat provides insulation that may hinder heat loss, and hot flashes and night sweats provide a way to dissipate that heat.

"Weight loss, especially loss of fat mass but not lean mass, might also help alleviate hot flashes and night sweats," added Kroenke.

The investigators emphasize that further research is needed to better understand the relationship between diet, weight and hot flash/night sweat symptoms. They explain that the beneficial impact of a healthy diet alone (regardless of weight change) may also help ameliorate symptoms.

This study follows a related study published in March in the Journal of Clinical Oncology in which Kaiser Permanente researchers found that preventing weight gain after a breast cancer diagnosis may offer a viable intervention for relief of hot flashes. The researchers noted that intentional weight loss in breast cancer survivors requires further study.

The Women's Health Initiative Dietary Modification trial enrolled a diverse group of 48,835 post-menopausal women between 1993 and 1998 at 40 United States clinical centers to evaluate the effects of a low-fat dietary pattern on heart disease, breast and colorectal cancer, and fracture in post-menopausal women. The dietary intervention was aimed at reducing fat intake and increasing fruit, vegetable and whole grain intake. Although weight loss was not a goal, participants assigned to the intervention group lost on average 4.5 pounds between baseline and year one, compared to the control group.