How intermittent fasting affects hormonal changes in women

Intermittent fasting has proven to be an effective way to lose weight, but critics worry that the practice may negatively affect
women's reproductive hormones.
Now, a team of researchers at the University of Illinois at Chicago has published a study in the journal Obesity that brings new evidence
.

Researchers led by Krista Varady, professor of nutrition at UIC, followed an 8-week "warrior diet" intermittent fasting study of a group of obese women before and after menopause
.

The Warrior Diet stipulates a four-hour eating time limit per day, during which dieters can eat without counting calories until the next day to resume water
fasting.

By analyzing blood sample data, they measured differences in hormone levels between two groups of dieters, one who insisted for 4 hours and 6 hours, and the other who did not adhere to dietary restrictions
.

Valadi and her team found that after eight weeks, the dieters' levels of the sex-binding globulin hormone (a protein that carries reproductive hormones) did not change
.
The same goes for testosterone and androstenedione, a steroid hormone that the body uses to produce testosterone and estrogen
.

However, at the end of the trial, dehydroepiandrosterone (i.
e.
, DHEA) was significantly reduced in premenopausal and postmenopausal women, by about 14%.

DHEA is a hormone
prescribed by fertility clinics to improve ovarian function and egg quality.

Although the decline in DHEA levels was the most important finding in this study, DHEA levels remained within the normal range
at the end of 8 weeks in premenopausal and postmenopausal women.

"This suggests that in premenopausal women, a slight drop in DHEA levels must be weighed
against the proven benefits of lower weight fertility," Valadei said.
"The decline in DHEA levels in postmenopausal women can be worrisome because menopause has led to a sharp drop in estrogen, which is the main component of
estrogen.
However, a survey of participants showed that low estrogen levels after menopause did not bring any negative side effects, such as sexual dysfunction or skin changes
.
”

As an added benefit, because high levels of DHEA are associated with breast cancer risk, Valadey said modestly lowering DHEA levels may help reduce breast cancer risk
in premenopausal and postmenopausal women.

The study also measured levels of estradiol, estrone, and progesterone, all hormones that are essential for pregnancy but only in postmenopausal women because levels of these hormones are constantly changing
during the menstrual cycle of premenopausal women.
In postmenopausal women, these hormones did not change
after 8 weeks.

Throughout the study, women in both the 4-hour and 6-hour diets lost 3 to 4 percent of their body weight from their baseline, while the control group had little to no weight loss
.
Biomarkers of insulin resistance and oxidative stress also declined
in dieters.

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

Still, Varadei said: "I think it's a great first step
.
We observed thousands of premenopausal and postmenopausal women through different alternate-day fasting and time-restricted eating strategies
.
All it does is make people eat less
.
Shorten the time you eat and you naturally reduce calories
.
Much of the negative information about intermittent fasting comes from studies
in mice or rats.
We need more research to look at the effects
of intermittent fasting in humans.
”