By David Liu, PHD

Sunday Sept 9, 2012 (foodconsumer.org) -- Testosterone levels are lower in obese men, compared to those with normal weight men. Testosterone supplements are commonly used to help weight loss.  A new study in the journal Hypertension suggests that it is possible this supplement helps weight loss, blood pressure should be carefully monitored.

Jane F. Reckelhoff, Women's Health Research Center, University of Mississippi Medical Center and colleagues conducted the study to determine the cardiovascular and metabolic effects of chronic testosterone supplementation in male obese rats that started to decrease their testosterone at 22 weeks of age.

For the study, rats were treated with testosterone supplements for 10 weeks.  It was found that testosterone supplements increased plasma levels of testosterone by 10-fold in both obese rats and lean rats.  

In obese rats, testosterone supplements promoted weight loss, reduced plasma insulin and cholesterol levels and improved their performance on the oral glucose tolerance test.  But the hormone also increased mean arterial pressure in obese rats.

None of these parameters including mean arterial pressure were influenced in lean rats.  Side effects observed in lean rats supplemented with testosterone included increased proteinuria and accelerated renal injury.  These side effects were not seen in obese rats supplemented with testosterone.

The researchers say in their report that "treatment of obese men with chronic testosterone supplements should be done with careful monitoring of blood pressure."

Testosterone supplements are available in the market as weight loss supplements.   But the safety profile of this product remains unknown. The current study suggests that it is possible that use of testosterone supplements can increase blood pressure among other things.