A new scientific review suggests that GLP-1 weight-loss drugs such as Ozempic, Wegovy and Mounjaro may do more than help with obesity. The review, published as a summary piece in Nature and presented at the Endocrine Society’s annual meeting in Chicago, found early signs that these medicines could improve reproductive health in men with obesity, including higher testosterone and better sperm quality.
The evidence is still preliminary. Researchers led by Dr. Pratibha Natt of the University of Warwick in Britain found only five randomized controlled trials that met their criteria. In one study of 30 men with obesity and low testosterone, both the GLP-1 group and the testosterone replacement therapy group saw testosterone rise after 16 weeks. In another study of 25 men with type 2 diabetes and hypogonadism, testosterone increased in both groups over 24 weeks, but the rise was greater with testosterone therapy, while the GLP-1 group showed better fertility measures.
The clearest change was in sperm quality. Among men given GLP-1 drugs, the share of sperm with normal shape rose from 2% to 4%, and other sperm-quality measures also improved. By contrast, men treated with testosterone had lower sperm count and poorer sperm quality, a known side effect of hormone treatment. Three other short studies in healthy men found no meaningful effect on testosterone.
Nature also cited additional studies in the same direction, including data from more than 1,600 men presented at the American Urological Association meeting, where testosterone reportedly rose about 30% after treatment with GLP-1 or similar obesity drugs. Another retrospective study of 215 men found testosterone levels were about 20% higher after weight-loss treatment. The researchers say the drugs may work indirectly by reducing fat, inflammation and insulin resistance, rather than acting directly on the testes. Dr. Natt called the findings a “wake-up call” for endocrinologists treating obese men with low testosterone, especially those planning children, but both she and other experts stressed that GLP-1 drugs are not yet a fertility treatment and need larger, longer studies before clinical guidance changes.
