News | Time-Restricted Eating: Weight Loss Without Changes in Sex Hormone Levels
Time-Restricted Eating: Weight Loss Without Changes in Sex Hormone Levels
A recent study published in the European Journal of Clinical Nutrition evaluated the effects of time-restricted eating (TRE) and calorie restriction (CR) on sex hormones.
Background
Time-restricted eating (TRE) is a weight-loss intervention that limits eating to a 4–10-hour window, followed by fasting with only calorie-free beverages. Despite potential health benefits, concerns remain about effects on sex hormones. Some studies suggest TRE may negatively affect estrogen, causing irregular menstrual cycles and fertility problems. Others suggest it may reduce testosterone, muscle mass, and libido in men. Evidence remains limited, and prior studies had small samples, lacked controls, lasted only a short time, and did not evaluate effects beyond two months.
Study Overview
Researchers compared the effects of TRE and CR on reproductive hormones in men and in premenopausal and postmenopausal women over 12 months. This was a secondary analysis of a published trial comparing the effects of CR and TRE on metabolic risk factors and body weight. Participants were aged 18–65 with a body mass index of 30–50 kg/m².
The study excluded smokers, pregnant women, people with diabetes, shift workers, perimenopausal women, people using an intrauterine device or hormone replacement therapy, and those whose weight had been unstable during the previous three months. Participants were randomly assigned to CR, TRE, or a control group. The trial included a six-month weight-loss phase and a six-month maintenance phase.
During weight loss, the TRE group ate freely from 12 p.m. to 8 p.m., then fasted until noon the next day with only calorie-free beverages. During maintenance, the eating window was extended from 10 a.m. to 8 p.m. The CR group reduced daily energy intake by 25% for six months, then consumed its calculated energy requirement for six months. The control group maintained usual exercise, diet, and weight.
Fasting blood samples were used to measure circulating total testosterone, dehydroepiandrosterone (DHEA), progesterone, estrone, estradiol, and sex hormone-binding globulin (SHBG). Changes between groups were compared using analysis of covariance, and associations between sex hormones and weight were assessed with Spearman or Pearson correlation coefficients.
Results
Of 126 people screened, 30 were randomized to the study groups. Ultimately, 77 participants completed 12 months, and analysis included 73 completers with sufficient blood samples. They included 10 men, 44 premenopausal women, and 19 postmenopausal women, with mean ages of 42, 39, and 56, respectively. After 12 months, weight decreased significantly in the TRE and CR groups versus controls, with no difference between TRE and CR. SHBG, DHEA, and total testosterone did not change over time or between groups in women or men. Progesterone, estradiol, and estrone did not change in postmenopausal women in either intervention group. Weight loss was not associated with changes in sex hormones.
Conclusion
Overall, TRE significantly reduced weight over 12 months but did not affect sex hormones in men or women with obesity compared with CR or the control group. Hormone changes may occur during the first months of an intervention and return toward baseline as weight stabilizes. Further research is needed to confirm these findings.
News | Time-Restricted Eating: Weight Loss Without Changes in Sex Hormone Levels
News | Time-Restricted Eating: Weight Loss Without Changes in Sex Hormone Levels
Time-Restricted Eating: Weight Loss Without Changes in Sex Hormone Levels
A recent study published in the European Journal of Clinical Nutrition evaluated the effects of time-restricted eating (TRE) and calorie restriction (CR) on sex hormones.
Background
Time-restricted eating (TRE) is a weight-loss intervention that limits eating to a 4–10-hour window, followed by fasting with only calorie-free beverages. Despite potential health benefits, concerns remain about effects on sex hormones. Some studies suggest TRE may negatively affect estrogen, causing irregular menstrual cycles and fertility problems. Others suggest it may reduce testosterone, muscle mass, and libido in men. Evidence remains limited, and prior studies had small samples, lacked controls, lasted only a short time, and did not evaluate effects beyond two months.
Study Overview
Researchers compared the effects of TRE and CR on reproductive hormones in men and in premenopausal and postmenopausal women over 12 months. This was a secondary analysis of a published trial comparing the effects of CR and TRE on metabolic risk factors and body weight. Participants were aged 18–65 with a body mass index of 30–50 kg/m².
The study excluded smokers, pregnant women, people with diabetes, shift workers, perimenopausal women, people using an intrauterine device or hormone replacement therapy, and those whose weight had been unstable during the previous three months. Participants were randomly assigned to CR, TRE, or a control group. The trial included a six-month weight-loss phase and a six-month maintenance phase.
During weight loss, the TRE group ate freely from 12 p.m. to 8 p.m., then fasted until noon the next day with only calorie-free beverages. During maintenance, the eating window was extended from 10 a.m. to 8 p.m. The CR group reduced daily energy intake by 25% for six months, then consumed its calculated energy requirement for six months. The control group maintained usual exercise, diet, and weight.
Fasting blood samples were used to measure circulating total testosterone, dehydroepiandrosterone (DHEA), progesterone, estrone, estradiol, and sex hormone-binding globulin (SHBG). Changes between groups were compared using analysis of covariance, and associations between sex hormones and weight were assessed with Spearman or Pearson correlation coefficients.
Results
Of 126 people screened, 30 were randomized to the study groups. Ultimately, 77 participants completed 12 months, and analysis included 73 completers with sufficient blood samples. They included 10 men, 44 premenopausal women, and 19 postmenopausal women, with mean ages of 42, 39, and 56, respectively. After 12 months, weight decreased significantly in the TRE and CR groups versus controls, with no difference between TRE and CR. SHBG, DHEA, and total testosterone did not change over time or between groups in women or men. Progesterone, estradiol, and estrone did not change in postmenopausal women in either intervention group. Weight loss was not associated with changes in sex hormones.
Conclusion
Overall, TRE significantly reduced weight over 12 months but did not affect sex hormones in men or women with obesity compared with CR or the control group. Hormone changes may occur during the first months of an intervention and return toward baseline as weight stabilizes. Further research is needed to confirm these findings.
Source:
Collected online