Weight loss surgery could be the key to revitalizing sex drive and fertility in obese men.
Excess weight interferes with natural sex steroid metabolism, converting testosterone into estrogen, in a process known as hypogonadism.
Until now, it has not been clear whether this effect on hormones could be significantly reversed.
But a new study on 29 men, presented today at the European Congress on Obesity in Vienna, has shown that weight loss after bariatric surgery does reverse obesity-related hypogonadism, and any dips in fertility and sex drive the men had experienced.
In fact, they found, the effects were seen within four weeks.
Excess weight crushes testosterone levels in men and drives up estrogen levels. This impacts sex drive and fertility – but weight loss after bariatric surgery can reverse that, a study shows
The goal of this study was to investigate levels of sex steroids immediately after rapid weight loss in a group of obese men who had undergone bariatric surgery, to determine how quickly those changes occurred.
Previous research has only evaluated the effects of weight loss surgery years after, so it was not clear what the relationship was between the body fat reduction and the hormone shift.
This study, however, tracked 29 men, with an average age of 40, from before their surgery to a month after.
They had an average body mass index of 43.4kg/m2 – above the obesity threshold of 40kg/m2.
One month beforehand, the team performed blood tests to track their total plasma testosterone, the sex hormones dihydrotestosterone (DHT), estradiol, luteinising hormone (LH), follicle-stimulating hormone (FSH), as well as sex hormone binding globulin (SHBG).
They also recorded their prostatic-specific antigen (PSA) levels, and leptin.
These tests were performed again after they underwent a sleeve gastrectomy to reduce the size of the stomach.
Another 19 healthy age-matched, non-obese males were also monitored as controls.
The majority obese subjects had lower testosterone levels than the healthy controls.
The study found that among the obese subjects, 51.6 percent had hypogonadism and of those who had subnormal total testosterone.
It was more common among those with metabolic syndrome, which leads to diabetes: 45 percent of them showed lower plasma testosterone, compared to men without metabolic syndrome.
Their BMI and waist circumference, however, did not determine testosterone levels.
A month after the sleeve gastrectomy, the obese subjects all showed a significant weight reduction, dropping an average of 17.2 kg.
Importantly, the proportion with hypogonadism had fallen to 11.6 percent.
Average testosterone levels increased by 85 percent – even to a higher level than in the healthy control group.
Estradiol levels fell by 35 percent while PSA levels rose by 70 percent.
The researchers say the study is a clear endorsement of bariatric surgery, and subsequent weight loss, as a treatment not only for excess weight but also hormonal issues that impact many other things.
‘The clinical significance of the rapid increase in PSA plasma levels observed one month after bariatric surgery is still obscure and has to be confirmed on a larger number of subjects and after a longer period of observation after surgery and weight reduction maintenance,’ the authors said.
They suggest that ‘it could be due to the rapid testosterone increase stimulating the prostate and/or to the rapid reduction in plasma volume after weight loss’.
They say: ‘If you consider that obese males, as with all people with obesity, have higher prevalence of some type of cancer, including prostate cancer for men, this information could be of importance, since it could lead to doctors potentially missing cases of severe prostate disease in obese men.’