Menopause and Midlife Weight Gain
Hormonal Changes Linked to Appetite Increase
Nov. 12, 2003 (NEW ORLEANS) -- It's well documented that as women go through menopause they tend to gain unwanted pounds but is there a link? The question remains controversial, but a new study offers compelling evidence that the hormonal changes associated with menopause may play a direct role in midlife weight gain.
Researchers from the Oregon National Primate Research Center report that monkeys who had their ovaries removed, resulting in a more rapid drop in female hormone levels as oppose to the gradual drops changes seen during the menopausal transition, had an almost immediate and dramatic increase in appetite that led to weight gain.
"This has been well documented in studies in smaller animals, but this is the first study to show that it is true in primates," researcher Judy L. Cameron, PhD, tells WebMD. "Studies in humans have been confounded by the fact that eating and exercise habits often change around the time of menopause."
Pears and Apples
It is clear that as we age there are age-related changes that slow our metabolisms. This, along with a decrease in physical activity can cause weight gain during menopause.
"We know that most women change from pear shaped to apple shaped as they age," says North American Menopause Society spokeswoman Pam Boggs. The 'pear' shape to 'apple' shape refers to a change in the distribution of where we carry our weigh -- whether it's predominately in the hips or around the belly. "But the evidence does not suggest that menopause on its own is associated with weight gain," she notes.
The study reported by Cameron, graduate student Elinor Sullivan, and colleagues included 47 adult female monkeys, 19 of whom have had their ovaries surgically removed. The surgery resulted in a drop in estrogen and progesterone levels, allowing the researchers to try to mimic the hormonal effects of menopause in these animals.
Within four weeks of having their ovaries removed, the monkeys had a 67% increase in food intake and a 5% increase in weight. The surgically altered monkeys also had higher levels of the hormone leptin than the monkeys who still had their ovaries. Leptin is produced by fat cells, and increases in body fat means more leptin is produced. This hormone has been shown to play a role in food intake and metabolism but how it does this remains largely unknown.
Researchers reported results at the annual meeting of the Society for Neuroscience in New Orleans. Findings from the same group of monkeys also show evidence against the popular belief that nighttime eating is associated with weight gain. The researchers found that monkeys who ingested most of their calories at night were no more likely to gain weight than those who ate more during the day.
Cameron says the idea that eating at night leads to packing on the pounds is an "urban myth" she has seen in countless fitness and women's magazines.
"This does not appear to be based on solid science, but it is a very popular notion," she says.