Study Reveals Impact of Time-Restricted Eating and Calorie Restriction on Sex Hormones

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

Time-restricted eating is a weight loss intervention, with a reduced eating window (4–10 hours) and fasting for the remaining time with energy-free beverages.

Despite the health benefits of time-restricted eating, there have been concerns about its impact on sex hormones. Some studies claim that time-restricted eating may negatively affect estrogen levels, which might lead to irregularities in the menstrual cycle and fertility issues. Similarly, research on males claims that time-restricted eating might reduce testosterone, muscle mass, and libido. However, the impact of time-restricted eating on sex hormones is largely unknown and requires further investigation.

For the study, researchers conducted a 12-month study to compare the effects of time-restricted eating (TRE) and calorie restriction (CR) on reproductive hormones in males and females. Participants were divided into three groups: caloric restriction, time-restricted eating, and control. The study had two phases: weight loss and maintenance, each lasting six months.

TRE participants ate freely from 12 PM to 8 PM and fasted until noon, later extending their eating window to 10 AM to 8 PM in the maintenance phase. The caloric restriction group reduced their daily energy intake by 25% initially, then consumed their calculated energy needs. The control group maintained their usual diet and exercise routines.

Fasting blood samples were collected to measure total testosterone, Dehydro-epiandrosterone (DHEA), progesterone, estrone, estradiol, and Sex hormone-binding globulin (SHBG) levels. Changes between groups were analyzed, and the relationship between sex hormones and body weight was examined.

The result showed significant weight loss in both the time-restricted eating and caloric restriction groups compared to the control group after 12 months, with no difference between time-restricted eating and caloric restriction. Sex hormone-binding globulin (SHBG), Dehydroepiandrosterone (DHEA), and total testosterone levels remained unchanged across all groups. In postmenopausal females, progesterone, estradiol, and estrone levels were also unchanged. Weight loss did not correlate with changes in sex hormones for either gender.

The findings suggested that time-restricted eating induces significant weight loss but does not affect sex hormones in males or females with obesity over 12 months compared to caloric restriction and controls. Changes in sex hormones might have occurred during the initial months of the intervention, which gradually returned to baseline levels as body weight stabilized over time.

Reference: Lin S, Cienfuegos S, Ezpeleta M, Pavlou V, Runchey MC, Varady KA. (2024) Effect of time restricted eating versus daily calorie restriction on sex hormones in males and females with obesity. Eur J Clin Nutr,. doi: 10.1038/s41430-024-01461-5. https://www.nature.com/articles/s41430-024-01461-5