Sperm quality not impacted by weight-loss surgery

May 1, 2011

Weight-loss surgery has no impact on obese men's poor sperm quality, despite improvements in their hormonal profile and sexual function.

Key Points

Campinas, Brazil-Weight-loss surgery has no impact on obese men's poor sperm quality, despite improvements in their hormonal profile and sexual function, according to a study from Brazilian researchers.

After 24 months of follow-up, men who underwent gastric bypass surgery had no significant changes from baseline in any parameters of sperm quality. Moreover, their sperm profile was similar to that of obese men who lost weight via lifestyle changes.

"Surgery-induced weight loss did not influence the spermogram profile, although it increased quality of sexual function, total testosterone, free testosterone, and follicle-stimulating hormone (FSH), and decreased prolactin levels," said first author Leonardo O. Reis, MD, a urologist at the University of Campinas in Campinas, Brazil. "The improved hormonal profile could explain the improvement in sexual function.

Obesity can adversely affect sexual function, hormone levels, and fertility in men. However, the impact of weight loss on those factors has received little attention in the medical literature. To examine the issues, Dr. Reis and colleagues studied 20 morbidly obese men whose BMI exceeded 40 kg/m2 (mean of about 55 kg/m2 ).

Half of the men initiated a supervised physical activity regimen and consumed a low-energy diet for 4 months, at which time they underwent gastric bypass surgery and continued follow-up for an additional 20 months. The remaining 10 men had weekly follow-up visits throughout the 24-month study. The primary endpoint was the change in sperm quality.

Baseline characteristics between the two groups did not differ significantly with respect to any clinical or laboratory values, including parameters of sperm quality and sexual function as assessed by the International Index of Erectile Function (IIEF). Baseline BMI averaged about 55 kg/m2 in both groups, and weight averaged 169 kg and 160 kg in the intervention and control groups, respectively.

After 4 months of follow-up, the intervention group had a mean BMI reduction of 12.7 kg/m2 and mean weight loss of 23.7 kg (p<.0001 vs. baseline). The control group had a mean BMI loss of 2.1 kg/m2 , which did not differ significantly from baseline.

No difference in sperm quality seen

Dr. Reis and colleagues evaluated multiple parameters of sperm quality: volume, vitality, pH, concentration, leukocytes, motility, and normal morphology. They found no statistically significant differences in any of the values, regardless of the measure they applied: mean, median, minimum, or maximum.

When the study ended, the intervention group had a mean BMI reduction of 24.7 kg/m2 compared with baseline and weight loss that averaged 73.5 kg. In contrast, the control group had almost no change from baseline for BMI or weight. The mean BMI differed significantly between the groups at 4 months (p=.0033) and at 24 months (p=.0006).

The surgery did produce favorable effects on sexual function and hormonal profile, however. The intervention group's mean IIEF score (normal=20) increased from 19.7 at baseline to 23.0 (p=.0469) at the end of the study, whereas the control group's score averaged about 17 at baseline and the end of the study. FSH and total testosterone values increased significantly in the intervention group but did not change in the control group. The mean prolactin value decreased significantly in the intervention group but not in the control group.