Weight loss medications, known as GLP-1s, may significantly improve sperm quality and testosterone levels in obese men, according to a recent analysis of studies. This finding could potentially transform fertility treatments by addressing obesity and metabolic health as root causes of male infertility.
Obesity is a major contributor to male infertility, affecting hormone levels, sperm production, and metabolism. These factors can impact the shape, motility, and count of sperm, making conception more difficult. Experts suggest that GLP-1s, the class of drugs that includes semaglutide (Wegovy, Ozempic) and liraglutide (Saxenda), could offer a way to restore hormone levels and preserve fertility by treating excess weight and poor metabolic health, rather than relying solely on testosterone replacement therapy (TRT).
"This work supports a shift away from prescribing testosterone replacement in men with obesity and low testosterone and towards treating the underlying cause - excess weight and poor metabolic health - which can naturally restore hormone levels and preserve fertility," said Dr. Pratibha Natesh, lead author of the study from Warwick Medical School.
The analysis, which examined five studies comparing GLP-1s to other treatments in men aged 18-65, found no negative impact on hormones, sexual function, or sperm quality. One 24-week study noted improvements in sperm shape and cholesterol levels with semaglutide while maintaining stable hormone levels. Another study showed that liraglutide increased testosterone levels in men with obesity-related low testosterone within four months, with better overall health outcomes compared to those treated with TRT alone.
These findings emerge as global sperm quality appears to be declining, with male infertility contributing to approximately half of all infertility cases, affecting about 7% of the male population. Researchers hope that highlighting the broader metabolic benefits of these drugs will encourage wider understanding.
Controversy Surrounding Testosterone Replacement Therapy
The study's authors noted concerns about the rise in TRT prescriptions, particularly driven by social media misinformation. In the UK, testosterone prescriptions increased by 135% between 2021 and 2024. Endocrinologists report seeing an increasing number of patients who have sought private testing and TRT, sometimes based on unfounded claims of boosting sex drive. This trend is reportedly straining healthcare services and leading to patients seeking unnecessary treatments.
Taking testosterone when not medically indicated can paradoxically lead to infertility by suppressing the necessary hormonal signals from the brain to the testes. This issue is compounded by the fact that infertility is often linked to poor health and obesity. Previous research has indicated that obese women are significantly less likely to conceive and have a higher risk of stillbirth.
Since the emergence of weight loss jabs, there have been reports of women becoming pregnant while using these medications, even after experiencing previous difficulties conceiving. While the exact mechanisms are still under investigation and more research is needed before GLP-1s can be formally marketed as fertility treatments, the initial findings suggest a promising avenue for improving male reproductive health by targeting metabolic factors.