Objective: To study the impact of a weight-loss program on sex hormones and sexual function among 38 middle-aged obese men (BMI >or=35 kg/m(2)).
Research methods and procedures: A randomized controlled clinical trial was conducted. The treatment group (n = 19) participated in a 4-month weight-loss program including 10 weeks on a very-low-energy diet (VLED) and 17 behavior modification visits. There was no intervention in the control group (n = 19). Both groups were followed for 8 months, i.e., 22 weeks after the active weight loss in the treatment group. The outcome measures (weight, sex hormones, sexual function, leptin, and metabolic variables) were obtained at baseline and at three time-points during follow-up.
Results: The mean weight loss in the treatment group was 21 kg at the end of the 10-week VLED. At the end of follow-up, the maintained weight loss was 17 kg of baseline weight. The control group was weight stable throughout the study. In the treatment group, increases in sex hormone-binding globulin, testosterone, and high-density lipoprotein-cholesterol, as well as decreases in insulin and leptin, were maintained until the end of follow-up, although with VLED, the level of several hormones and metabolic variables improved transiently during the rapid weight loss. There were no significant changes in the questionnaire scores on sexual function in either group.
Discussion: We conclude that obese men lose weight and increase their serum testosterone level on a weight-loss program with VLED and behavior modification. However, they do not change their sexual function scores.