Evaluation of the Impact of Functional Hypogonadism in Body Composition and Weight Loss in Men Undergoing Bariatric Surgery.

Abstract

Obesity and hypogonadism are linked in a vicious cycle: low testosterone levels favor weight gain and adiposity induces hypogonadism. We aimed to investigate if low levels of testosterone in pre-operative of bariatric surgery impacts postoperative weight loss (WL) and body composition (BC). A prospective, observational study included male patients who qualified for bariatric surgery. Patients underwent clinical evaluation, hormonal evaluation and assessment of body composition measured by dual energy X-ray absorptiometry in both pre-operative and postoperative periods. We evaluated 36 patients, mean age 37.1±10.2 years, weight 131.3±14.3 kg and BMI 44.4±4.95 kg/m2. Considering total testosterone (TT) <264 mg/dL and free testosterone <6.5 mg/dL (when TT was borderline), hypogonadism was found in 18 patients (50%). Among the 20 patients who underwent the total evaluation in the pre-operative period, the excess of weight was greater in hypogonadal men (58.1±1.,6 vs 51.1±13.5 kg) as well as the body fat percentage (BFP) (46.1±4.3 vs 45.1±4.5%), however, without statistical significance. After surgery, TT returned to normal in all hypogonadal patients, and patients showed similar WL and BFP. Regarding the relationship between visceral fat and testosterone, it was observed a moderate correlation between the change in TT levels and the reduction in visceral fat. Although frequently observed, low levels of TT in the pre-operative period do not impact post-surgical outcomes, in terms of WL or BC. The normalization of TT levels in the postoperative period is probably due to the gonadal function improvement provided by the WL after bariatric surgery.