Plenty of men who think they're doing everything right for their health may be quietly working against their fertility. For Men's Health Week (15 to 21 June 2026), we spoke to Dr Anand Patel, a GP with 26 years of experience and 15 years specialising in male sexual function, testosterone and fertility, about the gap between being fit for life and being fit for fertility.
His core message is reassuring: sperm renew roughly every three months, so the changes you make now can show up in your results within a single season. Here's what he wants men to understand.
Can you train too hard?
"There's fit for life and there's fit for fertility, and they're not the same thing," Dr Patel told us.
Moderate exercise is genuinely good for sperm. Jogging three times a week for around 30 minutes, or lifting moderate weights at roughly 70% effort, tends to improve sperm parameters, raise testosterone, build muscle and bone, and lower stress. The problems start at the extremes.
Very high-intensity training is where it tips over. Long-distance running, ultramarathons, circuits and high-intensity classes can reduce both sperm parameters and testosterone. As Dr Patel puts it, pushing yourself almost to the point of feeling sick signals to your body that this isn't the right moment to be a father. It makes evolutionary sense: your body deprioritises reproduction when it thinks you're under threat.
The heat problem
That heat point matters more than most men realise. Sperm is produced around three degrees cooler than core body temperature, which is why the testicles sit outside the body in the first place.
So anything that bakes or squashes them works against you: saunas after the gym, even sitting with your legs tightly crossed. Dr Patel's practical advice is to favour showers over hot baths while you're trying, choose loose boxers over tight underwear, and give things room to breathe. Good for life, less good for fertility, is a theme that runs right through his guidance.
Supplements: would you feed it to a baby?
When it comes to what you put in your body, Dr Patel offers a simple test: "What you're feeding yourself is potentially what's going to be used to construct a future baby. Would you feed that to a baby?"
By that measure, pre-workout fails. It's designed to spike your heart rate and blood pressure, pushing you towards the stress response and raising cortisol, which can work against fertility. Protein shakes are also worth pausing on. There's evidence linking them to poorer fertility parameters, so the advice is to get your protein from food where you can. If you do need to top up (for example, as a vegan or vegetarian), organic seed-based protein sources tend to be lower in additives and in phytoestrogens, the plant-based oestrogens that can occasionally disrupt sperm production in men.
Supplements aren't all bad, but more isn't better. Many fertility supplements are antioxidants, and while a little can help neutralise oxidative stress, too much tips you into reductive stress. Both extremes can damage the sperm's membrane, its genetic payload, or its tail. As Dr Patel summarises it: in the run-up to trying for a baby, put as few things as possible into your body that aren't actual food. Your creatine and protein shakes may be perfectly fine outside of that window.
How long is the run-up?
About three months. Men make a fresh batch of sperm roughly every 74 days, so changes need to be sustained rather than one-off.
"If you have a bit of a blowout at Christmas, that's not going to put things off track particularly," Dr Patel says. The bigger issue is constant habits. Heavy coffee intake, for instance, is associated with DNA fragmentation in sperm, where the tightly coiled genetic material snaps under stress. And "heavy" is easier to hit than you'd think: an espresso is one shot, but a medium high-street coffee can be four, so a couple of large coffees a day can quietly become eight to twelve shots. Regular heavy drinking is worth reining in for similar reasons.
The encouraging flip side is that three to four months of better habits can meaningfully improve sperm quality. And for men who genuinely can't change a factor long term, for example a job that requires hot protective gear, there's the option of cleaning things up for a few months and freezing sperm at the end of that window. Dr Patel is clear that none of this is about telling men off: "We're not here to bash people. It's difficult to change your lifestyle."
Testosterone and TRT: the myth that matters
This is where Dr Patel is most emphatic, because the stakes are high and the misunderstanding is common.
The instinct that "more testosterone means better fertility" is backwards. Testosterone inside the testicle is around a hundred times higher than in your bloodstream, and that concentration is what drives sperm production. But when you take testosterone from outside the body, whether a prescribed gel or something a mate suggested at the gym, your brain detects plenty of testosterone and stops sending the signals (FSH and LH) that tell the testicles to keep working. The factories go quiet, sperm production falls, and the testicles can shrink.
"Above two thirds of men on testosterone therapy, even within the normal range, will have suppressed their fertility if it's just testosterone itself," he explains.
The takeaway isn't that low testosterone should be ignored. It's that if you have low testosterone and want a family, the answer is a doctor who can prescribe treatment that works with your hormonal system rather than pure testosterone that works against it. As Dr Patel puts it, if anyone is offering you straight testosterone, by injection or gel, while you're trying to conceive, "that is not compatible." Always speak to the doctor who prescribes it before you start trying.
Sperm as a "canary in the coal mine"
One of the most striking parts of our conversation was Dr Patel's reframing of what a semen analysis really tells you.
Sperm quality reflects what's happening across your whole body: blood flow, nutrition, hormones and sleep all have to be working in tandem. That's why poor sperm parameters are increasingly linked to wider health risks. A Danish study following more than 78,000 men found those with the highest motile sperm counts lived around 2.7 years longer than those with the lowest, with better health in the years beforehand too.
"Your sperm is really a representation of what's going on in your whole body," he says. "It's the canary in the coal mine." A semen analysis, in other words, is useful information about your health, not just your fertility.
What this means in practice
If you and your partner are thinking about a family in the next few years, Dr Patel's advice is refreshingly un-dramatic. Prioritise sleep (he aims for eight hours, which means an earlier night than most of us manage). Keep exercise moderate. Lean towards a Mediterranean diet that's mostly unprocessed food, while accepting you don't have to be perfect. Keep an eye on waist circumference, since over 102cm raises the risk of diabetes, testosterone deficiency and other conditions. And keep heat, heavy coffee, pre-workout and external testosterone out of the picture during the three to four months you're actively trying.
His closing thought sums up the spirit of it: a baby isn't going to be relaxing for a few years either, so a few months of looking after yourself first is a fair trade for giving your future child the best start.
Frequently asked questions
Can too much exercise lower sperm count?
Yes. Very high-intensity training, ultramarathons and the like can reduce sperm parameters and testosterone. Moderate exercise, such as jogging three times a week or lifting moderate weights, tends to improve them instead. The issue is intensity and heat, not exercise itself.
Do protein shakes and pre-workout affect fertility?
There's evidence linking protein shakes to poorer fertility parameters, and pre-workout raises heart rate and cortisol in ways that can work against fertility. While trying to conceive, it's best to get protein from food and pause these supplements. They may be fine outside the conception window.
Does TRT affect fertility?
External testosterone signals the brain to stop telling the testicles to produce sperm, so more than two thirds of men on testosterone therapy suppress their fertility, even at normal doses. If you have low testosterone and want a family, ask your prescribing doctor about alternatives that support fertility.
How long does it take to improve sperm quality?
Around three months. Sperm renew roughly every 74 days, so sustained changes to diet, exercise, sleep, coffee and heat exposure can show up in a semen analysis within a single cycle.
How much coffee is too much for fertility?
It adds up faster than people expect. A single espresso is one shot, but a medium high-street coffee can be four, so two large coffees a day can mean eight to twelve shots. Heavy intake is associated with increased DNA fragmentation in sperm.
Thank you to Dr Anand Patel for sharing his expertise. The reassuring headline is that male fertility is far more changeable than most men assume, and three months of small, sustained adjustments can make a real difference.
If you'd like to know where you stand, our at-home sperm test with consultation gives you a clear picture of your reproductive health, analysed against World Health Organisation (WHO) guidelines and explained one-to-one by an NMC (Nursing and Midwifery Council) registered fertility nurse.
