Low testosterone can manifest itself in a number of ways. Some of the most common symptoms experienced are increased body fat, weakness, fatigue, loss of libido, mood disturbances, and erectile dysfunction.

Testosterone has a widespread impact on the way the body works and affects nearly all of the body’s systems. T plays a key role in metabolism, by affecting how the body uses its caloric intake and encouraging muscle protein synthesis. Excess abdominal fat can decrease the body’s levels of testosterone and boost estrogen production in males.

The most common reason for lowered T production is simply aging. Research has shown that testosterone levels in aging males fall 1-2% each year after age thirty.

Scientists have also found a link between low T and chemical imbalances in the brain, which may be why men with low T frequently report symptoms such as low libido, fatigue, and mood disturbances.

In recent years two different studies – one done by researchers at Saint Louis University and the other by the Kobe University Graduate School of Medicine in Japan – found that testosterone replacement therapy was an effective treatment for mild depression.