Study explores impact of intermittent fasting on female hormones

By Avery St. Onge

A recent study examined the effects of intermittent fasting on pre- and post-menopausal obese women and their hormone levels.

Previous research has shown intermittent fasting as an affective weight loss strategy. However, some scientists have expressed concerns over potentially negative impacts on female reproductive hormones. This study, published in the journal, Obesity, and led by Krista Varady, PhD, sought to discover whether the diet is harmful for female hormones.

Participants in the study followed a method of intermittent fasting known as the “warrior diet” in which dieters eat within a window of four to six hours a day without calorie counting. Participants followed the diet for eight weeks. After the trial period, researchers compared the differences in hormone levels, obtained from blood samples, of women who followed the diet and a control group who had no diet restrictions.

The study found that levels of the sex-binding globulin hormone, a protein that carries reproductive hormones throughout the body, were unchanged by the diet. In addition, levels of testosterone and a steroid hormone used to produce testosterone and estrogen, androstenedione, remained the same.

However, dehydroepiandrosterone (DHEA), a hormone that improves ovarian function and egg quality, was lowered by 14 percent in both pre- and post-menopausal women. While the drop was significant, researchers said the DHEA levels of participants were still in normal range by the end of the eight-week trial period.

“The drop in DHEA levels in post-menopausal women could be concerning because menopause already causes a dramatic drop in estrogen, and DHEA is a primary component of estrogen,” said Varady in a statement. “However, a survey of the participants reported no negative side effects associated with low estrogen post-menopause, such as sexual dysfunction or skin changes.”

For levels of estradiol, estrone, and progesterone, researchers found no significant changes due to the diet for post-menopausal women. These hormone levels were not tested in pre-menopausal women because levels change naturally throughout the menstrual cycle.

Participants who followed a time-restrictive diet experienced a three to four percent reduction in their baseline weight compared to the control group who had no weight loss. Dieters also showed a drop in insulin resistance and oxidative stress.

According to Varady, this study provides more insight into how intermittent fasting can impact women and their hormones. Yet, Varady said, further research is needed before official conclusions are made concerning the efficacy of restricted eating for women.