Yes. Being overweight causes testosterone levels to fall for several reasons. Firstly, testosterone is converted to the female hormone estrogen in fat tissue, and when there is too much fat there is a high rate of this conversion. Secondly, obesity is thought to suppress testicular function. Finally, testosterone is a fat-soluble hormone and is stored in fat tissue, so in an overweight man there may be too little testosterone in the blood because a higher-than-normal percentage is being stored in body fat. It is not clear in this setting whether the testosterone in the fat can be mobilized into the bloodstream as needed, or whether it is effectively prevented from being used. The good news is that all of the issues can be reversed with weight loss and obese men who lose weight often see a big rise in their blood testosterone levels, along with an improvement in their sexual interest and function.
