Thursday, July 28, 2005

Low-Fat Diet = Lower Testosterone in Men

Can it be true that eating a low-fat, high-fiber diet decreases testosterone in men?

Researchers at University of California-Los Angeles investigated the effects of a low-fat, high-fiber diet on 39 middle-aged, white, healthy men (50-60 yr of age). At the start they consumed their usual high-fat, low-fiber diet and then an 8-week modulation to an isocaloric low-fat, high-fiber diet.

The details of the findings on the high-fiber, low-fat diet includes:

  • Mean body weight decreased by 1 kg, whereas total caloric intake, energy expenditure, and activity index were not changed
  • Mean serum testosterone (T) concentration fell (P <>
  • Small but significant decreases in serum free T (P = 0.0045)
  • Small but significant decrease in 5 alpha-dihydrotestosterone (P = 0.0053)
  • Small but significant decrease in adrenal androgens (androstendione, P = 0.0135; dehydroepiandrosterone sulfate, P = 0.0011)
  • Serum estradiol and SHBG showed smaller decreases
  • Parallel decreases in urinary excretion of some testicular and adrenal androgens were demonstrated
  • Metabolic clearance rates of T were not changed
  • Production rates for T showed a downward trend while on low-fat diet modulation

The researchers overall conclusion was clear: We conclude that reduction in dietary fat intake (and increase in fiber) results in 12% consistent lowering of circulating androgen levels without changing the clearance.

Testosterone levels reach a peak during a man's twenties. Aging and lifestyle factors such as stress, improper diet, physical inactivity, smoking, drinking and the use of prescription medications can significantly reduce these levels.

Low levels of testosterone can result in:

  • sexual dysfunction
  • depression
  • fatigue
  • lack of energy
  • irritability and mood swings
  • loss of strength or muscle mass
  • increased body fat
  • hot flashes

Currently, the more subtle symptoms of low testosterone are commonly attributed to stress or the natural process of aging.

The evidence shows that a low-fat diet can lower testosterone in men. Following a good diet strategy is important not only for health reasons, but also for vitality. The IAS Bulletin recently included recommendations for a good diet strategy:

  • Eat moderate amounts of protein
    "Protein" in Latin means "above all else." Adequate protein is a dietary necessity as it stimulates testosterone release - it's also the fundamental building block for muscle repair and growth.
  • Eat more vegetables
    Especially green, leafy and cruciferous vegetables such as broccoli, cauliflower, kale, Swiss chard, Brussels sprouts, green leafy lettuce and cabbage. These vegetables contain phytochemicals essential for healthy metabolism of estrogen.
  • Limit your intake of refined, high-carbohydrate foods
    These include simple sugars such as cookies, candy and ice cream; and starches such as breads, potatoes and pasta. Excess intake of these carbohydrates raise blood sugar rapidly, creating chronically elevated levels of the hormones insulin and cortisol. These two hormones oppose the action of testosterone and diminish its production.
  • Eat healthy fats
    Essential fats such as the Omega 3 fatty acids (found in fish and flaxseed) and saturated fats are essential for normal testosterone production. All steroid hormones are produced from cholesterol and when fats are deficient in the diet, this process will be inhibited. Studies clearly indicate that low fat diets result in lower testosterone levels. Those higher in protein, lower in carbohydrate, and moderate in fat cause the greatest sustained levels of testosterone.
  • Take a high-quality, multi-vitamin mineral supplement
    Vitamins A, E, C and B6 and zinc are all used by the body in converting prohormones to testosterone. In fact, of all the minerals found in the body, zinc is the most crucial for testosterone production. Zinc deficiency is very common in the U.S. population, especially among athletes and the aged. Not only is zinc absent in most commercially-processed foods, it can be depleted from the body by alcohol and many prescription medications including diuretics.


  1. Anonymous4:28 PM

    Another compelling argument that reducing via lowering fat intake isn't necessarily good for hormone production.
    Thanks for the information about zinc!

  2. Keep healthy omega 3 and 6 fat intakes moderately high , these fats can help burn actual fat and keep testosterone levels pumpin. They can come from flax seeds or nuts.

    I would also recommend taking a zinc supplementation , as studies have shown it is required for proper testosterone production.

  3. You answered the exact question I had because I am in the same situation. Male, approaching 50, lifelong vegetarian, obsessed with eating high fiber low fat diet in a desperate effort to ward off diseases like hypertension and diabetes now finds himself with low T. This convinces me to try to include more healthy fats in my diet.

  4. maggie.danhakl@healthline.com6:32 AM


    Healthline just designed a virtual guide explaining how testosterone affects the body. You can see the infographic here:

    This is valuable med-reviewed information that can help a man understand how affects multiple parts of their bodies and the side effects that occur from having low testosterone. I thought this would be of interest to your audience, and I’m writing to see if you would include this as a resource on your page:

    If you do not believe this would be a good fit for a resource on your site, even sharing this on your social communities would be a great alternative to help get the word out.

    Thanks so much for taking the time to review. Please let me know your thoughts and if I can answer any questions for you.

    All the best,
    Maggie Danhakl • Assistant Marketing Manager
    p: 415-281-3124 f: 415-281-3199

    Healthline • The Power of Intelligent Health
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  5. Testosterone is known as the male hormone and everything that it connotes – “That man has an excess of testosterone – for good reasons. Declining testosterone levels usually cause significant physical and mental changes in a man, thus, the cause for concern.