New research presented at ENDO 2026 suggests that GLP-1 weight-loss medications may help restore hormones and sperm measures in men whose low testosterone is tied to obesity, while not appearing to suppress the core hormone axis that makes testosterone.
Obesity often disrupts the hypothalamic-pituitary-gonadal axis, which can drive down testosterone and harm semen quality. Scientists reviewed randomized trials to see whether popular GLP-1 drugs used for weight loss change reproductive hormones, sperm parameters, or metabolic markers in adult men. The goal was to untangle whether benefits come from weight loss itself or from direct effects of the medications.
The review included five randomized controlled trials that reported on testosterone, central hormones that regulate testicular function, and a carrier protein for sex hormones in the blood. Investigators also looked at sperm measures, body weight, cholesterol, and blood sugar changes in study participants. The data set is small, but it offers early clues about what happens to male reproductive health during GLP-1–driven weight loss.
Across the trials, GLP-1 drugs generally did not drive down male hormones. In fact, obese men with functional hypogonadism—meaning low testosterone likely linked to excess weight—often showed hormonal and sperm improvements as they lost weight on these medications. One short trial with dulaglutide reported no meaningful change in reproductive hormones or sexual function after four weeks.
Longer trials painted a more encouraging picture. A 16-week study with liraglutide found hormone improvements in obese men with low testosterone, and in some measures liraglutide outperformed hormone replacement approaches for overall health outcomes. Another liraglutide trial reported gains in sperm concentration and total count, which matters for men who want to preserve or improve fertility during treatment.
Semaglutide, available commercially as Ozempic and Wegovy, was tested in a 24-week trial that preserved total testosterone while improving sperm morphology and lowering bad cholesterol. These metabolic wins matter because obesity-related health issues can compound reproductive problems. Still, the authors caution that evidence is limited and varied across studies.
In an abstract of the research, the authors summed up that GLP-1s “do not appear to acutely suppress the male HPG axis and may improve reproductive hormones and semen parameters in obese hypogonadal men, largely within the context of weight loss.” “However, evidence remains limited and heterogeneous, underscoring the need for larger RCTs explicitly powered to assess male reproductive outcomes,” they wrote.
Clinicians not involved with the trials have noted the potential clinical implications. “This provides early evidence that GLP-1 medications taken by obese men with hypogonadism/low testosterone (low T) improves testosterone levels,” he said. Others emphasize that improving weight and metabolic health is a logical path to restoring hormone balance for many men.
Some experts argue GLP-1s could become a preferred strategy for obese men with low testosterone who want to preserve fertility, rather than using testosterone replacement that can suppress sperm production. “If this finding continues to gain evidence, GLP-1s might be a better option for low T than testosterone replacement therapy (TRT) in obese men – as GLP-1 medications preserve fertility, whereas TRT tends to be harmful to male reproductive/sperm function,” he added.
Bottom line, the small set of trials points toward neutral to positive reproductive outcomes for men using GLP-1 drugs while losing weight, but it is far from definitive. Larger, targeted randomized trials are needed to confirm whether benefits hold across diverse men and to separate weight-loss effects from direct drug actions on reproductive biology. Until then, healthcare providers should weigh individual fertility goals and metabolic needs when discussing these medications with male patients.
