Why Fat Loss Is the Best Way for Some Men to Boost Testosterone – and Why TRT Isn't Always the Answer

It feels like TRT is everywhere at the moment. Or at least, 'TRT' *wink wink* is everywhere – often used as a socially acceptable, medical-sounding way of saying: ‘I’ve decided to take anabolic steroids, but I’ve put it in a nice font.’

To be clear, testosterone replacement therapy is a legitimate medical treatment. For men with clinically low testosterone, properly diagnosed and properly supervised, it can be life-changing. But somewhere along the way, we seem to have skipped a few steps. Namely: are we sure your balls are broken, or are they just being crushed under the weight of your lifestyle?

Because a new study suggests that, for some men with obesity-related low testosterone, the most powerful intervention might not be adding more testosterone at all. It might be losing fat.

Researchers looked at men with obesity and metabolic hypogonadism – low testosterone linked to poor metabolic health – and split them into three groups. One group took tirzepatide, the weight-loss drug sold under brand names including Mounjaro. One group followed lifestyle advice. The third used transdermal testosterone replacement therapy. Everyone was also put on a calorie-controlled diet and asked to walk briskly for 20 minutes a day.

After two months, the tirzepatide group came out looking pretty compelling. They lost more weight, trimmed more from their waists, dropped more fat mass and improved erectile function scores. But here’s the really interesting part: they also saw the biggest improvements in total testosterone, free testosterone and bioavailable testosterone.

And, unlike simply adding testosterone into the system, their estradiol – a form of oestrogen – went down.

This is meaningful because body fat isn’t just ‘dead weight’. It’s still metabolically active tissue. Fat mass produces aromatase, an enzyme that converts testosterone into oestrogen. So, in layman’s terms the more excess fat you’re carrying, particularly around your middle, the more opportunity there is for your testosterone to be shunted down a hormonal side road.

In men, that can contribute to obesity-induced hypogonadism – clinically low T driven by poor metabolic health. In some cases, it can also play into symptoms such as gynaecomastia. Yes, ‘gyno’ or male breast tissue growth. The thing half of fitness Instagram talks about with the confidence of a consultant endocrinologist and the scientific rigour of a changing room rumour.

Now the elephant in the room here is obviously the usage of Tirzepatide. This does just sound a bit like swapping one drug for another, and we’re going to be pointed in saying that this doesn’t mean every man with low testosterone should run straight for a weight-loss jab. Tirzepatide is a serious medication, not a cheat code, and it comes with cost, both financially and in terms of side-effect considerations.

But the broader point is the bit we should probably pay attention to. If you’re overweight, under-slept, under-muscled, stressed to bits and living on beige food and energy drinks, TRT probably shouldn’t be your first move.

For genuine medical hypogonadism, speak to a proper doctor. Get bloodwork. Get assessed. Don’t outsource your endocrine system to a bloke on a podcast, please.

But for a lot of men, the less sexy answer may still be the best one: lose fat, build muscle, eat like you’re someone you care about, walk more, sleep properly and see what happens.

Sometimes the best way to raise testosterone isn’t to take testosterone. It’s to give your body fewer reasons to suppress it.

Hannah Bradfield

Senior Health and Fitness Writer

Hannah Bradfield is a Senior Health and Fitness Writer for Women’s Health UK. An NCTJ-accredited journalist, Hannah graduated from Loughborough University with a BA in English and Sport Science and an MA in Media and Cultural Analysis.  She has been covering sports, health and fitness for the last five years and has created content for outlets including BBC Sport, BBC Sounds, Runner’s World and Stylist. She especially enjoys interviewing those working within the community to improve access to sport, exercise and wellness. Hannah is a 2024 John Schofield Trust Fellow and was also named a 2022 Rising Star in Journalism by The Printing Charity.  A keen runner, Hannah was firmly a sprinter growing up (also dabbling in long jump) but has since transitioned to longer-distance running. While 10K is her favoured race distance, she loves running or volunteering at parkrun every Saturday, followed, of course, by pastries. She’s always looking for fun new runs and races to do and brunch spots to try.