Why low testosterone levels increase your risk of getting a pot belly...

Although testosterone is often considered a muscle-building hormone, it also plays an important role in helping you stay lean. In fact, researchers from the University of Washington have shown that men with low testosterone levels appear to be at greater risk of developing a "pot belly".

Low testosterone levels

More than 100 Japanese-American men took part in the research. A number of measurements, including total body fat and testosterone levels, were taken at the start of the study. The same measurements were taken again seven years later.

The research team found a link between testosterone levels at the start of the study and changes in visceral fat. In other words, visceral fat increased to a greater extent in the men starting the study with low testosterone levels.

Visceral (pronounced viss-er-al) fat surrounds and protects your internal organs. Subcutaneous (pronounced sub-cue-tain-ee-us) fat, on the other hand, is stored just under your skin. Not only does it look bad, visceral fat precedes the development of type II diabetes in Japanese Americans. It's also been linked to high blood pressure and heart disease.

Further evidence linking testosterone and body fat comes from the National Institute on Aging. Researchers tracked a group of men, aged between 65 and 88, for six months. Compared with those using a "dummy" supplement, treatment with testosterone reduced subcutaneous fat by around 7%.

Testosterone exerts a dual effect on fat loss by increasing the number of beta receptors, the parts of a fat cell that help to break down stored fat and prepare it for use as energy. Testosterone also inhibits the activity of lipoprotein lipase, an enzyme that plays a role in storing fat.

Diet

One way to reduce the risk of low testosterone is to make sure you're getting enough zinc in your diet. According to the US Department of Agriculture, 6 out of 10 men aged between 20 and 49 don't get enough zinc in their diet.

Because they tend to eat more, physically active people consume zinc in amounts exceeding the recommended daily amount (12 milligrams for women and 15 milligrams for men). However, certain groups (endurance athletes, for example) often consume a lot of carbohydrate. This can displace other foods — such as red meat — that contain high levels of zinc.

Unfortunately, it's difficult to establish whether you're getting enough zinc. Although measuring levels in the blood is one way to diagnose a severe zinc deficiency, it's not sensitive enough to establish a moderate zinc deficiency.

Good sources of zinc include sirloin steak (4.4 milligrams per 3 ounces), lamb chop (4 milligrams per 3 ounces), and turkey (2.6 milligrams per 3 ounces). Six large oysters provide over 20 milligrams of zinc. If you don't eat these foods on a regular basis, then a vitamin and mineral supplement can reduce your risk of a zinc deficiency.

However, as with all nutrients, too little as well as too much zinc isn't healthy. Zinc supplements in excess of 50 milligrams daily, for example, can interfere with the metabolism of copper.

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Reference
Tsai, E.C., Boyko, E.J., Leonetti, D.L., & Fujimoto, W.Y. (2000). Low serum testosterone level as a predictor of increased visceral fat in Japanese-American men. International Journal of Obesity and Related Metabolic Disorders, 24, 485-491