High Protein Intake May Lower Testosterone in Premenopausal Women

Despite Weight Loss, Ketogenic Diets Suppress Appetite
Despite Weight Loss, Ketogenic Diets Suppress Appetite
Eating more protein may lower testosterone levels in women.

A high-protein diet may reduce testosterone levels in healthy premenopausal women, according to research supported by the National Institute of Child Health and Human Development (NICHD).

Women with polycystic ovary syndrome (PCOS) who consume high amounts of protein can be affected by changes in steroidogenesis, likely by reducing hyperinsulinemia. The associations between protein intake and the production of certain hormones among premenopausal women without a history of infertility or PCOS, however, are not well understood. The NICHD conducted this study to examine the connection between protein intake and reproductive hormone concentrations in a healthy population.

The study, presented at the American Society for Reproductive Medicine (ASRM) Annual Meeting, included 259 healthy, premenopausal women who used fertility monitors for up to 2 menstrual cycles. Researchers measured estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, and testosterone levels up to 8 times per cycle.

The participants were asked up to 4 times per menstrual cycle about their protein consumption within the last 24 hours. The researchers calculated percent energy from total protein, animal protein, and vegetable protein.

The data showed that women with higher protein consumption, particularly animal protein, had lower testosterone levels.

The researchers divided the percent energy results into 3 groups and found that the highest tertile of percent energy from total protein intake had lower testosterone concentrations (beta, –0.05; 95% CI, –0.01 to –0.005) compared with the lowest tertile. The highest tertile of percent energy from animial protein also had lower testosterone (beta, –0.02; 95% CI, –0.04 to –-0.0001).

Study results revealed no additional association between protein intake and the other hormones evaluated, and there was no association between protein intake and ovulation.

“In the complex and delicately calibrated balance of hormones supporting the process of mammalian reproduction, abnormally low testosterone levels can have a deleterious effect on a female’s reproductive capacity,” ASRM President-elect Owen Davis, MD, said in a press release.

“We look forward to more findings and more detailed findings from the Biocycle Study.”


  1. Mumford SL, et al. Abstract O-1. Dietary Protein Intake and Reproductive Hormones and Ovulation: The Biocycle Study. Presented at: ASRM Annual Meeting; Oct. 17-21, 2015; Baltimore.