GLP1’s – The wonder drug for weight loss and sperm health?
It is well known that obesity is a global epidemic affecting around 650 million people! There is also irrefutable evidence around the impact of obesity on health including links to diabetes, cardiovascular disease, hypertension, cancer and crucially male infertility.
There is increasing evidence to show that men with a raised BMI are likely to face delays to conception and have less favourable results during assisted reproduction such as IVF. In addition, men with high BMI experience other sexual health related issues such as erectile dysfunction, hypogonadism and poor quality sperm.
While the link between obesity and sperm quality is complex, the impact on male hormones is clear. Excess abdominal fat doesn't just sit there; it acts like a metabolically and hormonally active organ. It contains an enzyme called aromatase, which has one specific job: converting testosterone into oestrogen (oestradiol).
For a man trying to conceive, this is a "hormonal hijack." Higher fat levels lead to higher oestrogen levels, which signal the brain to slow down testosterone production. This disruption to the Hypothalamus–Pituitary–Gonadal Axis (HPGA), the internal thermostat for your reproductive system, creates a hormonal environment that is the polar opposite of what healthy sperm production needs.
Furthermore, excess fat increases release of pro-inflammatory compounds (cytokines and adipokines), which in turn cause systemic oxidative stress. Oxidative stress is a leading cause of sperm DNA fragmentation, thus essentially damaging the genetic blueprint the sperm is carrying.
Yet, despite this, very little attention is given to a man’s weight when he seeks fertility treatment. Men are often dismissed with a casual "you should probably lose a little weight," with little acknowledgement of just how much impact weight loss could have on his fertility potential.
Managing weight loss – The new wonder drug
Losing weight is rarely easy. Between fad diets, shakes, and the constant noise of the weight-loss industry, many men feel lost. Boiling it down to its simplest terms, it is usually about eating the right type of food in moderation, balanced with exercise and movement. However, it is never that easy when so much of our food is ultra-processed and designed to bypass our natural fullness signals, making it incredibly hard to make informed decisions and healthy choices.
There is no doubt that we need to create a change in our society. With a healthcare system that is groaning under the pressure and with obesity being a major driver of so many chronic health conditions it’s no wonder that pharmaceutical companies and the NHS alike are looking for “easy” solutions to this epidemic.
GLP-1RAs (Glucagon-like peptide-1 receptor agonists) have been a game-changer, offering rapid weight loss and reversing many of the medical conditions associated with obesity. But as a relatively new tool in the fertility kit, do we know enough about how they work in the long term?
What are GLP1RA’s and how do they work?
GLP-1RAs mimic a natural hormone, Glucagon-like Peptide 1, your gut releases. This hormone acts as a signal to your pancreas to release insulin and tells your stomach to slow down, making you feel full and satisfied. By taking a GLP-1RA, patients can better control blood sugar, slow stomach emptying, and most importantly silence the "food noise" or cravings that make traditional dieting so difficult.
How does this help fertility?
Given what we know about hormonal disruption and oxidative stress, it’s easy to see how losing weight helps. As the fat melts away, the aromatase effect decreases, and testosterone levels naturally begin to rise. Hormone function returns to normal, blood sugar levels stabilise and inflammatory markers decrease. All of this helps create a healthier better environment for testicular function and sperm quality.
However, research shows that GLP-1RAs may also have a direct effect on the testes. Scientists have discovered that GLP-1 receptors are actually physically present on Leydig cells (the cells that make testosterone) and Sertoli cells (the "nurse" cells that grow sperm). This means the drug might be communicating directly with the "sperm factory," potentially protecting the blood-testis barrier and creating a healthier environment for sperm to develop.
Are there any long-term effects?
While the benefits are exciting, we must address the potential risks. As these medications are relatively new in the context of fertility, there are several areas where the science is still catching up:
1. The epigenetic question
One of the biggest "unknowns" is epigenetics. This refers to how your environment and the medications you take might change the "tags" on your DNA. Since sperm take about 72–90 days to develop, some experts are concerned about whether being on a powerful metabolic medication at the moment of conception could influence the health of the future child.
2. Muscle loss and Sarcopenia
GLP-1s are very effective at reducing weight, but that weight isn't always just fat. If a man loses significant lean muscle mass (sarcopenia) due to rapid weight loss, it can negatively impact his metabolic health and long-term testosterone levels. Maintaining a high-protein diet and resistance training while on these medications is vital for reproductive health.
3. The "Wash-Out" period
Because we don’t yet have decades of data on "GLP-1 babies," many fertility specialists recommend a wash-out period. Similar to how women are often advised to stop the medication two months before trying to conceive, some doctors suggest men do the same to ensure the sperm used for conception was produced in a "drug-free" environment.
4. Rapid weight loss "Shock"
Extremely rapid weight loss can temporarily cause a dip in sperm quality. As fat stores break down, they can release stored toxins into the bloodstream, and the caloric deficit can lead to temporary nutrient deficiencies. It is a marathon, not a sprint.
The rebound effect
Now, that GLP1RA’s have been around just long enough for people to have “miracle” results, we are beginning to see what happens when people stop the medication.
As is so often the case, many people regain the weight that was lost and in many instances they put on additional weight beyond their pre GLP1RA weight.
The body has a way of "keeping score." When pushed into a massive caloric deficit, your metabolism can adjust to protect you, and it will remember times of deficit. This is why many people regain the weight (and then some) once they stop the medication or any other “crash” diet. If the weight returns, all that goes with it also returns.
For this reason, dietary changes, lifestyle alterations, and regular exercise should always remain the first line of defence. GLP-1RAs should be viewed as a powerful kickstart to a healthier lifestyle, rather than a standalone cure and should always be offered alongside counselling and psychological support.
In summary
There is no doubt that GLP-1RAs offer a unique, fast-acting lifeline for men struggling with obesity and infertility. By restoring hormonal balance and directly supporting testicular function, they can significantly improve the chances of conception.
However, patients must be mindful that this medication is still relatively new. It works best when combined with nutritional support and a long-term plan to ensure that once the weight is gone, it stays gone for the health of the father and the future child.
Research reviewed
Cannarella R, Calogero AE, Condorelli RA, Greco EA, Aversa A, La Vignera S (2021); Is there a role for glucagon-like peptide-1 receptor agonists in the treatment of male infertility? Andrology 9(5): 1499-1503
Oliveira-Lopes B, Braga PC, Oliveira PF, Alves MG, Bernardino RL (2025); A pharmacological dose of liraglutide improves mitochondrial performance in mouse Leydig cells. Int J Mol Sci 26(18): 8903
Pereira TA, Thaker N, Rubez AC, Lima VFN, Bernie HL, Esteves SC (2025); Managing obesity-related male infertility: insights from weight loss intervention. Hum Reprod 40(11): 2027-2037
Salvio G, Ciarloni A, Ambo N, Bordoni M, Perrone M, Rossi S, Balercia G (2025); Effects of glucagon-like peptide 1 receptor agonists on testicular dysfunction: A systematic review and meta-analysis. Andrology 13(8): 2022-2034
Varnum AA, Pozzi E, Deebel NA, Evans A, Eid N, Sadeghi-Nejad H, Ramasamy R (2023); Impact of GLP-1 agonists on male reproductive health-A narrative review. Medicina (Kaunas) 60(1): 50
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