According to findings from a new study presented at the Integrative Biology of Exercise 7 meeting in Phoenix, Arizona, overweight to obese men using a combination of healthy eating and exercise significantly increased their level of testosterone.  This important finding is crucial since testosterone begins to decline by 1 percent each year starting sometime between age 30-40. 

Testosterone is the male sex hormone and when men have low circulating testosterone levels this can lead to various health problems for them.  One of the factors escalating testosterone levels to decline is obesity.  Low testosterone levels can lead to fatigue, reduced sex drive, reduced muscle mass and strength, low bone density, depression, and lack of self-confidence.

The research team from Tsukuba University in Japan wanted to determine if regular aerobic exercise by itself would have an effect on testosterone levels in overweight to obese men.  They recruited 44 men, 28 who were overweight or obese and 16 who were of normal weight.  None of the men participated in regular exercise.

Before the study started, each man’s testosterone levels were measured and then after the study, they were measured again. 

The study had the men engage in aerobic exercise which included 40-60 minutes of walking or jogging 1-3 days each week for 12 weeks. 

The results from the study showed that for the men who were of normal weight there was no difference in their testosterone levels with the addition of exercise.  However, the men who were overweight to obese had significant increases in their testosterone levels at the end of the 12 week period. These men saw their total testosterone levels increase from 15.4 nanomoles per liter to 18.1 nanomoles per liter.  The more vigorous they exercised, the higher the increase in their testosterone levels.

Even though the overweight to obese men’s testosterone levels increased while the normal weight men’s testosterone levels remained the same, the testosterone levels of the overweight to obese men were still lower than the normal weight men’s levels.

At the end of the 12 week study there was a small degree of weight loss among the men.  Weight loss can be a factor for helping to increase serum testosterone levels in men but since the amount of weight lost was not as significant, the study demonstrated that increasing vigorous physical activity was the main factor for the increase in testosterone levels in the overweight to obese men.