Effects of timed eating and calorie restriction on sex hormones

A recent study published in the European Journal of Clinical Nutrition examined the effects of time-restricted eating (TRE) and caloric restriction (CR) on sex hormones.

Study: Effect of time-restricted eating versus daily calorie restriction on sex hormones in obese men and women.  Image credit: Effect of time-restricted eating versus daily calorie restriction on sex hormones in obese men and women.. Image credit:

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TRE is an intervention to reduce body weight, with a reduced eating window (4-10 hours) and fasting for the rest of the time with energy-free drinks.

Despite the health benefits of TRE, there have been concerns about its effect on sex hormones. In other words, some studies say that TRE can negatively affect estrogen levels, which can cause menstrual irregularities and fertility problems.

Similarly, research on men says that TRE can reduce testosterone, muscle mass and libido. However, the effect of TRE on sex hormones is largely unknown due to the lack of literature.

In addition, the trials were small, lacked control, and were short in duration, with no study examining outcomes beyond two months.

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In the present study, the researchers evaluated the effects of TRE on reproductive hormones in men and women before and after CR compared with CR, and no intervention was performed for months of 12.

This was the second analysis of a published trial comparing the effects of CR and TRE on metabolic risk factors and body weight. People aged 18-65, with a body weight between 30 kg / m2 and 50 kg/m2 were included.

Individuals were excluded if they were smokers, pregnant, diabetic, shift workers, perimenopausal, using an intrauterine device, using hormone replacement therapy, or have had an irregular weight gain in the past three months. Subjects were randomized to CR, TRE, or control groups. The trial included weight loss and maintenance measures for six months each.

TRE subjects ate ad libitum between 12 and 8pm and fasted thereafter with soft drinks until noon the next day for the first six months. During the maintenance phase, the TRE window was extended (10 am to 8 pm).

On the other hand, the CR group reduced their energy intake by 25% every day for the first six months and used their calculated energy needs for the next six months.

Controls were asked to maintain regular exercise, eating habits, and weight. Fasting blood samples were collected; circulating levels of total testosterone, dehydroepiandrosterone (DHEA), progesterone, estrone, estradiol, and sex hormone-binding globulin (SHBG) were measured.

Two-way analysis of covariance compared changes between groups. The relationship between sex hormones and body weight was analyzed using Spearman or Pearson correlation coefficients.


126 participants were evaluated; 30 people were selected from the study groups. Of these, 77 participants completed the 12-month study; Analyzes were limited to 73 respondents who had sufficient blood for hormone measurements.

Of them, 10, 44, and 19 were men and women before and after menstruation, with an average of 42, 39, and 56, respectively. Significant weight loss was observed in the TRE and CR groups relative to controls at month 12.

However, there was no difference between the CR and TRE groups. SHBG, DHEA, and total testosterone levels in women and men did not change over time and between groups.

Progesterone, estradiol, and estrone were measured in postmenopausal women only; their status did not change in the intervention groups. Furthermore, weight loss was not associated with changes in sex steroids in both men and women.


Overall, TRE caused significant weight loss but did not affect sex hormones in obese men or women over 12 months compared to CR and controls.

Changes in sex hormones may have occurred during the first months of the intervention, which gradually returned to baseline levels while body weight remained stable over time. However, more research is needed to confirm these results.

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