Weight loss jabs boost testosterone and could improve fertility in men, study finds
Weight loss jabs could transform fertility treatment, experts say, after a study linked the jabs to improved testosterone levels and sperm quality in men.
It’s well known that living with obesity increases the risk of a number of serious health conditions, from diabetes to cancer.
But it’s also a major cause of male infertility – altering hormone levels, affecting sperm production and causing problems with metabolism, according to a group of UK researchers.
Left untreated, this can impact the shape, movement and number of sperm men have, making it increasingly difficult to conceive.
Now early research has shown that weight loss jabs, known collectively as GLP-1s, could significantly boost sperm quality and the male sex hormone testosterone in obese men.
Experts say the findings could transform the treatment of low testosterone, a condition that is closely linked to obesity.
In recent years, the UK has seen a rise in private firms offering testosterone replacement therapy, which has a number of unpleasant side effects.
‘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,’ Dr Pratibha Natesh, study lead from Warwick Medical School, said.
Clinical trials suggest GLP-1s may improve fertility in men with obesity
It comes as sperm quality appears to be declining around the world – with male infertility contributing to approximately half of all cases and affecting 7 per cent of the male population.
The researchers hope that by offering clear, evidence based information about the drugs, people will realise that ‘improving metabolic health can have positive effects far beyond weight loss alone.’
Experts from the University Hospitals Coventry and Warwickshire analysed five studies that compared GLP-1s to other treatments in men aged 18-65.
While the researchers were mainly concerned with changes in testosterone and other hormones that control testicular function, they also examined sperm quality, body weight, blood sugar and cholesterol levels and overall metabolic health.
Results showed that GLP-1s have no negative impact on hormones, sexual function or sperm quality.
For example, one 24-week study found that semaglutide – the active ingredient in Wegovy and Ozempic – led to improvements in sperm shape and cholesterol levels, while keeping hormone levels stable.
Another study found that in men with obesity-related low testosterone levels, liraglutide – sold under the brand name Saxenda – increased levels in just four months.
Their overall health outcomes were also better than those who were treated with testosterone replacement therapy (TRT) alone.
The controversial influencer, Clavicular, now has over 760,000 followers on TikTok. But by his own account, years of testosterone abuse has cost him his fertility
TRT is a prescription-only treatment recommended under national guidance for men with a clinically proven deficiency.
But, in recent years, social media misinformation has led to an uptick in men searching for testosterone therapy they don’t need – based off claims it will boost their sex drive – adding pressure to already stretched services.
In the UK, testosterone prescriptions rose by 135 per cent between 2021 and 2024, with endocrinologists now seeing patients who have had private blood tests – often promoted on social media – every week.
Prof Channa Jayasena, of Imperial College London, chair of the Society for Endocrinology Andrology Network, told the Guardian: ‘These patients are filling our clinics.
‘We used to see people with adrenal problems and diabetes, and it’s really affecting NHS care. We are all asking how to deal with this.’
The controversial influencer, Clavicular, whose real name is Braden Peters, 20, became famous for the lengths he has gone to to have achieved his appearance.
By his own account, Peters – who began his ‘looksmaxxing’ journey at just 14-years-old – is now infertile as a result of years of testosterone abuse.
Now experts say that TRT may not be the answer, and men should first focus on treating underlying causes, such as excess weight and poor metabolic health.
Crucially, taking the hormone when not needed can cause infertility – suppressing the testicular and hormonal signals from the brain needed for the testicles to work.
Infertility is known to be linked to bad health and obesity, with previous research suggesting that obese women are over a third less likely to become pregnant and twice as likely to have a stillbirth than healthy-weight women.
Since weight loss jabs emerged on to the scene, there has been a whole registry dedicated to women who have got pregnant on Wegovy, despite previously struggling to conceive.
It’s long been known that carrying excess weight negatively affects fertility in several ways – from inhibiting ovulation to reducing sperm quality – but more research is needed before the revolutionary drugs can be marketed as a fertility treatment.
