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The Impact of Low-Fat Diets on Testosterone Levels: What You Need to Know

ByHuman Health Co.
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Diet culture, along with many doctors and dietitians, often champion low-fat diets as the foundation of a healthy lifestyle. However, emerging scientific evidence challenges this claim. Studies suggest that low-fat diets dramatically decrease testosterone levels leading to a multitude of physical and mental health complications.

Fat provides significantly more bioavailable nutrients than carbohydrates or protein. Low-fat diets can often result in nutrient deficiencies, which may negatively impact testosterone production in both men and women. As awareness grows, it’s becoming clear that low-fat diets may contribute to lower testosterone levels1. In this article, we unpack the impact of low-fat diets on testosterone levels.

Testosterone Plays a Role in the Following:

  • Sexual health – sex drive (libido), sexual satisfaction, genital arousal, ability to orgasm, and overall ability to enjoy sex
  • Muscle mass/strength
  • Fat distribution and storage
  • Bone density
  • Fertility
  • Menstrual cycles (women)
  • Sperm production (men)
  • Energy levels
  • Female menopausal symptoms – hot flashes, night sweats, mood changes
  • Development of male characteristics during puberty – deep voice, hair growth on the chest, armpits, face, head, and pubic area.
  • Skin health
  • Vaginal health – vaginal dryness
  • Mental health
  • Red blood cell production

Low-Fat, Low Testosterone in Both Men and Women

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The link between low-fat diets and reduced testosterone levels is strongly supported by scientific evidence. A study involving men and premenopausal women found that men on a low-fat vegetarian diet experienced a decrease in nocturnal release of testosterone2 and prolactin—a hormone crucial for maintaining hormonal balance. Similarly, women following the same diet showed reduced nocturnal prolactin levels and an even greater decline in plasma dehydroepiandrosterone (DHEA), – a hormone used to make testosterone and estrogen.

Low-fat diets are associated with increased bodily inflammation. Even when research participants were given dexamethasone—a medication designed to combat inflammation linked to low-fat diets—both men and women still experienced reductions in prolactin and testosterone-related hormones. This highlights the persistent hormonal impact of a low-fat diet.

High-Fat Diet Increased Testosterone

In a study involving 39 middle-aged men (ages 50-60), participants switched from a high-fat, low-fiber diet to a strict low-fat, high-fiber diet for 8 weeks3. During this time, they experienced significant decreases in serum androgens (male sex hormones), urinary androgens, and testosterone production. Even with minor weight loss, total serum testosterone dropped by 12%, and free testosterone decreased by 10%. Remarkably, when the men returned to their regular high-fat, low-fiber diet, their testosterone levels normalized within 8 weeks.

Low-Fat = Low Testosterone, Why It Makes Sense

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The biomechanics are straightforward: a low-fat diet lacks adequate nutrition and cholesterol, which is the primary building block for testosterone4. Without sufficient cholesterol, the body cannot produce testosterone. In simple terms: no cholesterol equals no testosterone, and low cholesterol results in low testosterone.

Nutrient deficiencies are closely linked to low testosterone levels, with B vitamins, particularly B12, playing a significant role in hormone regulation for both men and women. A study of men and women with anemia found that both groups were more likely to have low testosterone than participants who were not anemic.

Another study involving 154 men with low testosterone revealed that 76% were deficient in vitamin B125. Foods naturally rich in bioavailable B12—such as meat, eggs, and milk—are also typically high in fat, making them common exclusions in low-fat diets and contributing to low testosterone levels.

Consequences of Low Testosterone in Men

Low testosterone (low T) levels can have far-reaching consequences. Men with low T often face diminished sexual function, including erectile dysfunction, infertility, low libido, or a complete loss of sex drive. Cognitive and emotional health is also affected, with many experiencing depression, reduced mental clarity, lack of motivation, and lethargy6. Physical changes include muscle wasting, decreased strength, increased belly fat, and reduced bone density, potentially leading to osteoporosis if levels remain low.

Emerging research links low T to obesity, non-alcoholic fatty liver disease, insulin resistance (a precursor to type 2 diabetes), and higher risks of all-cause and cardiovascular-related death7. This connection is logical, as low T is associated with increased visceral fat, which disrupts organ function and contributes to the development of cardiometabolic conditions over time.

Mental Health Consequences of Low Testosterone in Men

Low testosterone also impacts men’s mental health and overall outlook on life, regardless of age. Low T has been associated with depressive symptoms and a variety of mood disturbances. These symptoms can range from dysthymia (persistent mild depression) and fatigue to more severe manifestations, including inertia, listlessness, hopelessness, and even suicidal thoughts.

Testosterone levels also play a role in anxiety-related traits. Conditions can range from generalized, unfocused fear to phobic anxiety and full-blown panic syndromes8. This suggests that testosterone influences both mood and mental health, contributing to a broad spectrum of emotional and psychological experiences, emotional resilience, and daily functioning.

Consequences of Low Testosterone in Women

Low testosterone (low T) in women is commonly linked to sexual dysfunction, impacting multiple aspects of sexual health, including libido, climax ability, vaginal dryness, genital arousal, sexual enjoyment, and, in some cases, fertility. Beyond sexual health, low T is associated with chronic inflammatory conditions, such as metabolic syndrome (a precursor to type 2 diabetes), cardiovascular disease, and increased mortality risk9.

Low testosterone also significantly impacts brain health and function in women. Low T has been linked to an increase in beta-amyloid, a protein that forms plaques in the brain, causing brain cell death and leading to brain atrophy10. Elevated beta-amyloid levels can also reduce brain cell glucose metabolism and blood flow to the brain, both of which are associated with the development and progression of Alzheimer’s disease.

Low T also contributes to reduced bone density, a condition more pronounced in women than in men. Women begin losing bone density around age 30, compared to men, who typically experience this decline after age 50. Within the first five years post-menopause, women lose an estimated 10% of their bone density11. Testosterone plays a vital role in producing osteoblasts—cells responsible for bone growth. A study of 1,058 post-menopausal women showed a clear link between low testosterone levels and reduced bone density. Consequently, women with low T are at a significantly higher risk of developing osteoporosis.

The Impact of Low-Fat Diets on Testosterone Levels

The low-fat diet trend began in the 1970s when federal guidelines recommended reducing fat intake while increasing consumption of vegetables, fruits, whole grains, and lean protein. Since then, testosterone levels in men have declined by an average of 1% annually over the last 50 years12. In the 1940s, studies showed that the average testosterone level in men was around 700 ng/dl13. Today, that average has dropped to 400 ng/dl. 80 years ago, before the low-fat diet trend, it was a rarity to see testosterone levels at 250 ng/dl in men under 80. Now such levels are a common finding in middle-aged men.

Food Photography of Sliced Bacon on Top of Brown Chopping Board -Testosterone Levels

Testosterone is essential for overall health, influencing sexual function, body composition, and mental and metabolic health. Low testosterone has been linked to conditions such as sexual dysfunction, obesity, type 2 diabetes, and metabolic syndrome. As testosterone levels drop, the body experiences a gradual decline in performance and functionality.

Fortunately, there’s a tasty way to address this. Replace bread, pasta, cereals, salads, and low-fat meats/dairy with nutrient-dense options like a juicy ribeye. Choose bacon and eggs over bagels, buffalo wings over chicken breasts, and fatty brisket over a turkey sub. With these changes, you will likely see improvements in testosterone levels, energy, libido, muscle mass, bone strength, vaginal health, sperm quality, and mental health.

Supporting Research

  1. Whittaker, J., & Wu, K. (2021, March 16). Low-fat diets and testosterone in men: Systematic review and meta-analysis of Intervention Studies. The Journal of Steroid Biochemistry and Molecular Biology. https://www.sciencedirect.com/science/article/abs/pii/S0960076021000716
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  2. Hill, P. B., & Wynder, E. L. (2005, October 14). Effect of a vegetarian diet and dexamethasone on plasma prolactin, testosterone and dehydroepiandrosterone in men and women. https://www.sciencedirect.com/science/article/abs/pii/S0304383579800543 ↩︎
  3. Christina Wang, Don H. Catlin, Borislav Starcevic, David Heber, Christie Ambler, Nancy Berman, Geraldine Lucas, Andrew Leung, Kathy Schramm, Paul W. N. Lee, Laura Hull, Ronald S. Swerdloff, Low-Fat High-Fiber Diet Decreased Serum and Urine Androgens in Men, The Journal of Clinical Endocrinology & Metabolism, Volume 90, Issue 6, 1 June 2005, Pages 3550–3559, https://doi.org/10.1210/jc.2004-1530 ↩︎
  4. The truth about cholesterol: Good, Bad, or Misunderstood?. Human Health Co. (2024, August 12). https://humanhealthco.com/the-truth-about-cholesterol-good-bad-or-misunderstood/ ↩︎
  5. Cui T, Terlecki R. Prevalence of Relative Deficiencies in Testosterone and Vitamin B12 Among Patients Referred for Chronic Orchialgia: Implications for Management. Am J Mens Health. 2018 May;12(3):608-611. doi: 10.1177/1557988316642723. Epub 2016 Apr 8. PMID: 27059628; PMCID: PMC5987952. ↩︎
  6. Jia H, Sullivan CT, McCoy SC, Yarrow JF, Morrow M, Borst SE. Review of health risks of low testosterone and testosterone administration. World J Clin Cases. 2015 Apr 16;3(4):338-44. doi: 10.12998/wjcc.v3.i4.338. PMID: 25879005; PMCID: PMC4391003.  ↩︎
  7. Hu TY, Chen YC, Lin P, Shih CK, Bai CH, Yuan KC, Lee SY, Chang JS. Testosterone-Associated Dietary Pattern Predicts Low Testosterone Levels and Hypogonadism. Nutrients. 2018 Nov 16;10(11):1786. doi: 10.3390/nu10111786. PMID: 30453566; PMCID: PMC6266690. ↩︎
  8. Zitzmann M. Testosterone, mood, behaviour and quality of life. Andrology. 2020 Nov;8(6):1598-1605. doi: 10.1111/andr.12867. Epub 2020 Jul 30. PMID: 32657051. ↩︎
  9. Bianchi VE. The Anti-Inflammatory Effects of Testosterone. J Endocr Soc. 2018 Oct 22;3(1):91-107. doi: 10.1210/js.2018-00186. PMID: 30582096; PMCID: PMC6299269. ↩︎
  10. What happens to the brain in Alzheimer’s disease? | National Institute on Aging. (n.d.). https://www.nia.nih.gov/health/alzheimers-causes-and-risk-factors/what-happens-brain-alzheimers-disease ↩︎
  11. Yang J, Kong G, Yao X, Zhu Z. Association between Serum Total Testosterone Level and Bone Mineral Density in Middle-Aged Postmenopausal Women. Int J Endocrinol. 2022 Aug 17;2022:4228740. doi: 10.1155/2022/4228740. PMID: 36034179; PMCID: PMC9402345. ↩︎
  12. Lokeshwar SD, Patel P, Fantus RJ, Halpern J, Chang C, Kargi AY, Ramasamy R. Decline in Serum Testosterone Levels Among Adolescent and Young Adult Men in the USA. Eur Urol Focus. 2021 Jul;7(4):886-889. doi: 10.1016/j.euf.2020.02.006. Epub 2020 Feb 18. PMID: 32081788. ↩︎
  13. Caronia LM, Dwyer AA, Hayden D, Amati F, Pitteloud N, Hayes FJ. Abrupt decrease in serum testosterone levels after an oral glucose load in men: implications for screening for hypogonadism. Clin Endocrinol (Oxf). 2013 Feb;78(2):291-6. doi: 10.1111/j.1365-2265.2012.04486.x. PMID: 22804876. ↩︎

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