Research finds weight loss in boys with obesity improves testosterone levels

A study, published in the European Journal of Endocrinology, and conducted by researchers at both Saint Louis University School of Medicine and University of Buffalo has found that adolescent boys with obesity who lose weight following bariatric surgery improve their testosterone levels.

Sandeep Dhindsa, M.D., a SLUCare endocrinologist and the director of SLU’s Division of Endocrinology, Diabetes and Metabolism, and first author on the paper stated, “Boys with obesity do not achieve sufficient testosterone levels at puberty and weight loss can theoretically improve testosterone. We checked the testosterone levels in boys with obesity who underwent bariatric surgery. Those who lost weight had increased testosterone levels. Those who regained weight had a lowering of testosterone again.”

In the study, researchers evaluated the changes in sex hormones following bariatric surgery in 34 male patients between the ages of 14 to 19. These participants were part of a long-term multi-centre study, the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS). Teen-LABS is the first large study to systematically document the outcome of metabolic bariatric surgery for treatment of adolescents with severe obesity in the United States.

Following surgery the participants were followed for five years. Total testosterone, estradiol, luteinizing hormone, follicle stimulating hormone, sex hormone binding globulin, insulin and glucose were all measured before surgery, six months’ post-operative and annually thereafter. 

The study showed that bariatric surgery, in addition to treating obesity and reversing Type 2 diabetes, reversed low testosterone levels.

“Males usually achieve their peak testosterone concentrations at puberty, followed by a gradual decline for the rest of their life. Adolescent males with obesity start off with a lower testosterone. We do not know the long-term effects on fertility and sexual function. Testosterone is also important for muscle and bone growth. Our study provides strong evidence that weight loss can restore normal testosterone concentrations in these boys,” Dhindsa said.

73% of participants had subnormal free testosterone levels prior to surgery. Only 20% had subnormal free testosterone concentrations two years later. That percentage rose to 33% due to regained weight among some participants five years later.

Common causes of low testosterone in adults are ageing, obesity and diabetes. Male adults with obesity have lower testosterone levels than adults who are of a lean weight.