Researchers have found that intermittent fasting may affect women’s reproductive hormones. A study published in the journal Obesity summarized these findings.
The ‘warrior diet’ technique of intermittent fasting was used to monitor a group of obese pre-and post-menopausal women for eight weeks, led by UIC Nutrition Professor Krista Varady.
What is warrior diet?
On the warrior diet, dieters have a four-hour window each day during which they can eat freely without counting calories before beginning their water fast.
Blood samples from dieters who adhered to four- and six-hour feeding windows and a control group who didn’t follow dietary restrictions were used to measure hormonal differences.
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Drop in DHEA levels may be concerning
Varady and her team found that after eight weeks of dieting, the dieters’ levels of sex-binding globulin hormone, a protein that transports reproductive hormones, were unchanged. Interestingly, both testosterone and androstenedione, which produce both testosterone and oestrogen in the body, behaved the same way.
DHEA (Dehydroepiandrosterone) levels were found to be 14 percent lower in pre-and post-menopausal women in the study. This is the hormone that fertility clinics recommend to improve ovarian function and egg quality.
Varady pointed out that a decrease in DHEA levels in pre-menopausal women has to be weighed against the proven effects of a lower body mass on fertility. Considering that DHEA is a primary component of estrogen, the drop in DHEA levels in post-menopausal women may be concerning.
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Low estrogen post-menopause, however, didn’t seem to cause negative side effects such as sexual dysfunction or skin changes. Also, Varady pointed out that since women with high DHEA levels are at a higher risk for breast cancer, a moderate drop may help lower this risk.
As part of the study, estradiol, estrone, and progesterone levels were also measured. However, these levels were only measured in post-menopausal women because the levels of these hormones fluctuate during the menstrual cycle of pre-menopausal women.
All of these hormones are essential for the development of pregnancy. These hormones did not change after eight weeks in post-menopausal women.
Study participants in the four- and six-hour dieting groups lost between 3 and 4% of their starting weight over the course of the study, compared to almost no weight loss in the control group.
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The dieters also reported decreased oxidative stress biomarkers and insulin resistance. There were no women in the study who were in their 40s and were perimenopausal.
Varady believes this is a great first step. “We have observed thousands of pre- and post-menopausal women with alternate-day fasting and time-restricted eating methods. All it does is make you eat less. By shortening the eating window, you will naturally reduce your calorie intake,” said Varady.
Studies on mice and rats have provided most of the negative information regarding intermittent fasting. More studies are required in order to study the effects of intermittent fasting on humans, stated Varady.