The latest generation of weight-loss medications may offer an unexpected benefit beyond helping people shed pounds: improved male fertility. According to a systematic review presented at the Endocrine Society’s annual meeting in Chicago, GLP-1 receptor agonists may increase testosterone levels and improve sperm quality in men with obesity.
Researchers caution that the evidence remains preliminary. More rigorous clinical trials are needed to confirm the connection, said review co-author Dr. Pratibha Natesh, an endocrinologist at Warwick Medical School in the United Kingdom. Still, the findings add to a growing body of research suggesting that GLP-1 drugs may positively affect male reproductive health.
Can GLP-1 Weight Loss Drugs Improve Testosterone in Men?
Researchers are beginning to explore whether GLP-1 medications—such as semaglutide (Ozempic, Wegovy) and liraglutide (Saxenda, Victoza)—may offer benefits beyond weight loss and blood sugar control. One possible benefit is improving testosterone levels in men with obesity or type 2 diabetes.
Yes, GLP-1 receptor agonists (such as semaglutide and tirzepatide) have been linked to significant increases in testosterone levels for men. Clinical data indicates these medications can reverse low testosterone by improving metabolic health, independent of weight loss alone. Recent endocrinology and urology research has established a strong connection between GLP-1 use and hormone levels. A large retrospective analysis found that men on GLP-1 therapy saw their median total testosterone jump from 320 ng/dL to 419 ng/dL, and free testosterone rise from 9.0 ng/dL to 10.4 ng/dL. While losing abdominal fat improves hormone health, researchers found that testosterone improvements occurred even after adjusting for BMI, suggesting GLP-1s offer direct endocrine benefits. In an 18-month study of men with obesity and type 2 diabetes, the number of participants with testosterone levels in the healthy, normal range climbed from 53% to 77%
Why Testosterone Matters
Testosterone is an important hormone that helps regulate:
- Muscle mass and strength
- Energy levels
- Sex drive and sexual function
- Fertility
- Metabolism and overall health
Men with obesity and type 2 diabetes often have lower testosterone levels, a condition sometimes called functional hypogonadism.
What the Researchers Did
The researchers reviewed studies published through December 2024 that examined testosterone levels in men before and after treatment with GLP-1 drugs.
They analyzed four studies involving a total of more than 200 men who were treated with GLP-1 medications.
What They Found
The analysis showed that men taking GLP-1 medications experienced:
✅ Higher levels of bioavailable testosterone, the form of testosterone that the body can readily use.
✅ Better blood sugar control, as reflected by lower HbA1c levels.
However, the researchers did not find clear evidence that GLP-1 drugs significantly increased:
- Free testosterone
- Sex hormone-binding globulin (SHBG), a protein that affects testosterone availability
Why Might GLP-1 Drugs Help?
Researchers believe the benefits may be linked to:
- Weight loss
- Reduced body fat
- Improved insulin sensitivity
- Better overall metabolic health
Because obesity and insulin resistance can suppress testosterone production, improving these conditions may help restore hormone levels.
Could GLP-1 Drugs Be an Alternative to Testosterone Therapy?
Testosterone replacement therapy (TRT) is currently the standard treatment for low testosterone. However, TRT can carry risks and side effects, including:
- Increased red blood cell counts
- Worsening sleep apnea
- Potential cardiovascular concerns
GLP-1 drugs may offer a different approach by addressing underlying causes of low testosterone, such as obesity and insulin resistance.
Important Limitations
The findings are encouraging, but there are several reasons for caution:
- Only four studies were included.
- The studies involved relatively small numbers of patients.
- Different GLP-1 medications and dosing schedules were used.
- Results were not always consistent across studies.
Because of these limitations, researchers say larger, better-designed clinical trials are needed before doctors can conclude that GLP-1 drugs reliably improve testosterone levels or fertility.
Bottom Line
Early evidence suggests that GLP-1 medications may increase the amount of usable testosterone in men with obesity or type 2 diabetes while also improving blood sugar control. However, the research is still preliminary, and more studies are needed to determine whether these drugs can be used specifically to treat low testosterone or improve male fertility.
GLP-1 medications, including many of the obesity treatments introduced over the past several years, mimic the naturally occurring hormone glucagon-like peptide-1. By activating GLP-1 receptors, these drugs reduce appetite, slow digestion, and promote weight loss. To examine the impact of GLP-1 drugs on male fertility, Natesh and her colleagues reviewed randomized controlled trials that measured testosterone levels in men taking these medications. They identified five studies that met their criteria.
One study involved 30 men with obesity
One study involved 30 men with obesity and hypogonadism, a condition characterized by low testosterone levels. Participants were randomly assigned to receive either a GLP-1 medication or testosterone replacement therapy (TRT). After 16 weeks, testosterone levels had increased in both groups.
A second study followed 25 men with type 2 diabetes and hypogonadism who were randomly assigned to receive either a GLP-1 drug or TRT. After 24 weeks, testosterone levels rose in both groups, although the increase was larger among those receiving testosterone therapy. However, the GLP-1 group experienced improvements in sperm quality. The percentage of sperm with normal morphology doubled from 2% to 4% during the study. In contrast, sperm count and quality declined among participants receiving TRT, a well-documented effect of testosterone therapy.
Healthy men who received GLP-1 medications for shorter periods
The remaining three studies included healthy men who received GLP-1 medications for shorter periods and found no significant changes in testosterone levels. Additional research supports the review’s findings. At the American Urological Association’s annual meeting in Washington, D.C., researchers from the Mayo Clinic reported that men prescribed GLP-1-based obesity medications experienced testosterone increases of approximately 30%. The analysis included more than 1,600 men and evaluated both traditional GLP-1 drugs and newer medications that target GLP-1 along with glucose-dependent insulinotropic polypeptide (GIP).
Scientists say the results are biologically plausible. Obesity is strongly associated with lower testosterone levels, which can impair sperm production and fertility. One reason is that fat tissue contains high levels of an enzyme that converts testosterone into estradiol, the primary female sex hormone. Obesity-related inflammation and metabolic dysfunction can also interfere with testosterone production.
Symptoms of low testosterone
Natesh believes the findings should encourage physicians to take a broader view when treating men with obesity and symptoms of low testosterone, particularly those hoping to conceive. Symptoms of low testosterone can include reduced libido, depressed mood, fatigue, and loss of muscle mass.
The emerging evidence suggests that addressing obesity through lifestyle changes and, when appropriate, GLP-1 medications may help restore testosterone levels without immediately resorting to testosterone replacement therapy. In many cases, weight loss alone may be enough to improve hormonal function. “I see many patients in this situation,” Natesh said. Her message to clinicians is straightforward: rather than prescribing testosterone immediately, “look at the broader picture.”