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Avoid Soy and Eat Some Meat

In your never-ending quest for packing on slabs of beef—or as we science guys call it, “lean body mass”—look to science to show you the way, as well as show you what not to do. First, let’s check out the latest in testosterone.

We know big T is the king of all anabolic hormones (step aside, insulin) because it’s also catabolic with regard to fat. Studies on testosterone administration are as prolific as wildebeest in the African savanna. For instance, a recent study looked at the effect of testosterone therapy on insulin sensitivity, substrate metabolism, body composition and lipids in aging men who also had low normal bioavailable testosterone.

A randomized, double-blind, placebo-controlled study of testosterone treatment with a gel form of the hormone was done on 38 men, aged 60 to 78. They found that lean body mass increased while high-density-lipoprotein cholesterol and total bodyfat decreased in the testosterone but not placebo group. Fat burning at rest increased, and basal glucose oxidation decreased in response to testosterone therapy, even when corrected for changes in lean body mass.

So when you give older men testosterone (particularly those who are on the low end), it can increase muscle mass and fat burning.1 Contrary to reports in the mainstream press, clearly there is a beneficial role for testosterone. On the other hand, you’ve heard reports about how soy might have a negative effect on men. For real? Let’s see what the science says.

A number of reports demonstrate adverse effects of isoflavones due to their estrogenlike properties. Scientists presented a case report of a 19-year-old type 1 diabetic but otherwise healthy man who experienced a sudden loss of sex drive and erectile dysfunction after taking in large quantities of soy-based products while on a vegan diet. Scientists took blood counts of free and total testosterone and dehydroepiandrosterone—a.k.a. DHEA—at the initial exam and monitored him for up to two years after he stopped eating the vegan diet. Blood concentrations of free and total testosterone were initially decreased, whereas DHEA was increased. Those parameters normalized within one year after he gave up being a vegan.

Normalization of testosterone and DHEA was paralleled by a constant improvement of symptoms—he regained full sexual function in a year. At least if you go by this man’s experience, it is apparent that using soy products is related to low testosterone and erectile dysfunction. This is the first report of a combination of decreased free testosterone and increased DHEA blood concentrations in someone following a soy-rich diet.2

Bottom line: If you want to stay manly, avoid the soy and eat some meat.


Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (; also check out


1 Frederiksen, L., et al. (2011). Testosterone therapy increased muscle mass and lipid oxidation in aging men. Age (Dordr). In press.

2 Siepmann, T., et al. (2011). Hypogonadism and erectile dysfunction associated with soy product consumption. Nutrition. In press.



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