*2.12.3 Male sex hormones*

Severe obesity in male patients is accompanied with abnormal sex hormone levels and male hypogonadism. Evidence showed a negative impact of excessive BMI on testosterone levels, sexual function and sperm parameters [48]. LSG is associated with improvement in sexual and reproductive health, and may ameliorate the sex hormone unbalance seen with obesity [49]. The total testosterone levels were significantly increased at 1, 3, 6 months after BS (13.1 ± 7.0, 13.6 ± 5.7, 21.0 ± 19.3 nmol/L, respectively), and estradiol levels significantly decreased at 6 months after surgery (91.4 ± 44.9 pmol/L) [49]. WL with LSG also has favorable effects on semen parameters of patients with pre-existing azoospermia and oligospermia [50]. There was a significant increase in the sperm concentration in men with azoospermia and oligospermia 1 year post LSG (both P < 0.05) [50]. Interestingly, the changes in semen and hormones were not affected by the extent of WL experienced by the patients, suggesting an independent mechanism [50].
