How does intermittent fasting affect female hormones?

Intermittent fasting has been shown to be an effective way to lose weight, but critics worry that the practice may have a negative impact on women’s reproductive hormones. Now, a group of University of Illinois Chicago researchers has published a study in Obesity that brings new evidence to the table.

Researchers led by UIC nutrition professor Krista Varady followed a cluster of pre- and post-menopausal obese women through the “warrior diet” of intermittent fasting for eight weeks.

The warrior diet envisions a four-hour-a-day time-restricted diet that dieters can eat without counting calories before continuing the water fast until the next day.

They measured the differences in hormone levels obtained by analyzing blood sample information in groups of dieters fitted with four- and six-hour feeding predictions versus a control set with no dietary restrictions.

After eight weeks, Varady and his group found that levels of sex-binding globulin, a protein that carries reproductive hormones throughout the body, did not change in dieters. The exact same thing was true for both testosterone and androstenedione, a steroid hormone that the body uses to produce both testosterone and estrogen.

However, dehydroepiandrosterone, or DHEA, a hormone prescribed by fertility clinics to improve ovarian function and egg quality, was significantly lower in both premenopausal and postmenopausal women at the end of the trial, dropping by about 14%.

While the decrease in DHEA levels was the most valuable finding of the study, DHEA levels in both premenopausal and postmenopausal women remained in the usual range at the end of the eight-week respite.

“This suggests that the small reduction in DHEA levels in pre-ladies must be weighed against the proven fertility benefits of lower body mass,” Varady said. Said. “The decline in DHEA levels in postmenopausal women can be worrisome, as menopause actually causes a dramatic drop in estrogen and DHEA is the primary component of estrogen. However, a survey of participants reported no adverse side effects associated with low estrogen post-abortion – such as sexual dysfunction or skin changes.”

As an added benefit, as it’s linked to a higher risk of DHEA, Varady said, a moderate reduction in levels can help reduce this risk for both premenopausal and postmenopausal women.

The study also measured levels of estradiol, estrone, and all hormones vital to pregnancy, but only in postmenopausal women because of the varying levels of these hormones throughout premenopausal women’s menstrual cycles. There were no random changes in these hormones at the end of eight weeks in postmenopausal women.

Ladies in both the four-hour and six-hour sets experienced weight loss of 3% to 4% of their baseline load over the course of the study, compared with the control set, which lost almost no weight. Dieters also saw a decrease in insulin resistance and biomarkers of oxidative stress.

Perimenopausal women, typically in their 40s, were excluded from the study.

Still, Varady says, “I think this is an extraordinary first step. We have observed thousands of women before and after menopause with fasting and time-restricted eating strategies on different days. All it does is make people eat less. By shortening this eating interval, you naturally reduce calories. More than one of the negative information reported about it comes from studies in mice or rats. We need to examine the effects of intermittent fasting on more human studies.”

Story Source: materials provided by. Brand new written by Laura Fletcher.