The newest obesity medications may offer an additional advantage: enhancing male fertility. A systematic review unveiled at the Endocrine Society’s annual conference in Chicago, Illinois, indicates that GLP-1 drugs could potentially boost testosterone levels and improve sperm quality in men suffering from obesity.
Although the findings are initial and require further detailed trials for verification, co-author Pratibha Natesh, an endocrinologist at Warwick Medical School in Coventry, UK, notes that other emerging studies align with these results.
Perfect Sperm
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Most of the recent obesity treatments released in the last five years operate by engaging the same receptor as glucagon-like peptide 1 (GLP-1), a natural hormone that induces a sense of fullness. To understand their impact on male fertility, Natesh and her team reviewed literature for randomized controlled trials of GLP-1 drugs that recorded testosterone levels in men, identifying just five studies.
(This article uses ‘men’ to reflect the language used in the review and other studies, while recognizing that not all people who have sperm identify themselves as men.)
In one trial, 30 obese men with low testosterone, a condition known as hypogonadism, were randomly given either a GLP-1 drug or testosterone replacement therapy (TRT). After 16 weeks, both groups experienced a rise in testosterone levels.
Another study randomly assigned 25 men with type 2 diabetes and hypogonadism to either a GLP-1 drug or TRT. After 24 weeks, testosterone levels had risen in both groups, though more significantly in those receiving TRT. However, the GLP-1 group showed improved sperm quality, with the percentage of morphologically normal sperm increasing from 2% to 4%. Conversely, the TRT group saw a decline in sperm count and quality, which is typical during such therapy.
The remaining three studies reviewed involved healthy men using GLP-1 drugs briefly, showing no effect on testosterone levels.
Testosterone Boost
The review’s conclusions are corroborated by other research, including a study presented at the American Urological Association’s annual meeting in Washington DC by Andrés Guillén-Lozoya from Mayo Clinic in Rochester, Minnesota. His analysis of electronic health records of over 1,600 men prescribed obesity drugs found a roughly 30% increase in testosterone levels following treatment with either a GLP-1 drug or a combined GLP-1 and glucose-dependent insulinotropic polypeptide drug.
A retrospective analysis of electronic health records from 215 men treated with weight-loss medications also showed an average testosterone level rise of about 20% post-treatment.
Fat Cells’ Effect
Experts are not surprised that these drugs may influence male fertility. Obesity is known to reduce testosterone, a critical hormone for sperm production and fertility. This reduction is partly due to fat cells containing high levels of an enzyme that converts testosterone into oestradiol, the primary female sex hormone. Additionally, metabolic alterations and increased inflammation from obesity can impact testosterone production.
Natesh emphasizes that these findings should alert endocrinologists treating men, particularly those aiming to conceive and dealing with both obesity and low testosterone symptoms like reduced libido, depression, and muscle loss. For individuals with low testosterone, tackling obesity through lifestyle changes and potentially weight-loss drugs is a viable approach. Often, these interventions alone can restore testosterone levels.
“I encounter many patients in this situation,” Natesh adds. She advises colleagues treating individuals with obesity and low testosterone to avoid prescribing “testosterone immediately, look at the broader picture.”
This article is reproduced with permission and was first published on June 15, 2026.
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