A new study suggests that drugs like Ozempic may do more than lower blood sugar and aid weight loss, they could also raise testosterone levels in men. 

Researchers from S. Louis University Hospital found that men taking GLP-1 medications, including semaglutide (Ozempic) and tirzepatide (Mounjaro), saw their testosterone levels increase by 24 percent after 18 months of treatment. 

Testosterone is a vital hormone responsible for male sexual development, muscle mass, bone density, red blood cell production, and fat distribution.

Low testosterone is common in men with obesity or Type 2 diabetes and is linked to fatigue, reduced libido, and decreased quality of life.

The new findings suggest that GLP-1 drugs may also improve reproductive health in men affected by these conditions.

Researchers say the results open the door for further investigation into how anti-obesity medications can impact hormone levels and overall well-being.

Lead author Dr Shellsea Portillo Canales, an endocrinology fellow at SSM Health St Louis University Hospital said: ‘While it is well known that weight loss from lifestyle changes or bariatric surgery increases testosterone levels, the impact that anti-obesity medications may also have on these levels has not been widely studied.’

‘Our study is among the first to provide compelling evidence that low testosterone can be reversed with the use of commonly prescribed anti-obesity medications.’ 

Apart from reducing blood sugar levels and weight, regularly taking Ozempic may also increase your testosterone levels

The researchers analyzed existing medical records of 110 adult men with obesity or Type 2 diabetes. 

All of the participants were being treated with semaglutide (Ozempic or Wegovy), dulaglutide (Trulicity) or tirzepatide (Zepbound) for one and a half years.

All three drugs are known to mimic the effects of GLP-1, a natural hormone in the body that regulates blood sugar and appetite, often leading to lower blood sugar and weight loss. 

None of the men were on testosterone or hormonal therapy before or during the experiment. 

Some risks of testosterone therapy include worsening sleep apnea, acne, enlarging the prostate or breasts, increasing the growth of prostate cancer, reducing sperm counts, causing the testicles to shrink and increasing the risk of clots, according to the Mayo Clinic.

The researchers measured the participants’ total and free testosterone levels before and during their treatment.

Results showed that the participants experienced 10 percent of weight loss and saw their testosterone levels rise from 53 percent to 77 percent.

The scientists are yet to discover how GLP-1 drugs can increase testosterone.

Researchers from the St Louis University Hospital have found that men experienced an increase of testosterone levels by 24 percent when they took anti-obesity medications for 18 months

However, previous research has shown that excess fat can force the body to convert testosterone into estrogen, a female hormone.

But when obese individuals start to lose weight, they reduce their body fat stores, which can improve insulin sensitivity in the body and reduce overall inflammation.

Both decreased inflammation and weight loss can help the body produce more testosterone and prevent the conversion of the male hormone into estrogen.

Talking about the preliminary results, Dr Portillo Canales said: ‘Results from this study show that there is a direct correlation between the use of anti-obesity medications and testosterone levels.

‘Doctors and their patients can now consider this class of medications not only for the treatment of obesity and to control blood sugar, but also to benefit men’s reproductive health.’

But despite clear results, the study authors noted that further research is needed to establish a clear link between the drugs and an increase in testosterone.

However, seeing how beneficial the discovery is, Dr Fatima Cody Stanford, an obesity medicine physician scientist at Massachusetts General Hospital who was not involved in the study, told NBC News: ‘The findings from this study highlight an important intersection between metabolic health and hormonal balance.

‘This dual benefit underscores the potential of these medications to enhance overall health outcomes, including reproductive health, in this population.’

Average testosterone levels in men are between 300 to 1,000 nanograms per deciliter. 

Testosterone tends to decline gradually with age, starting around the late 30s to early 40s. 

By the age of 75, the average male testosterone level drops to about 65 percent of the average level seen in young adults, Dr Portillo Canales said.

The findings were presented today at ENDO 2025, the Endocrine Society’s meeting in San Francisco.