It was late August when Serena Williams posed for a picture that provoked thousands of words and left a few more unsaid.
The image faced no difficulty in catching the eye, considering how few athletes, active or otherwise, choose to pose with a needle.
But there she is in the photograph, with a pen injector containing weight-loss medication held against the triceps of her left arm. Three years have passed since one of sport’s greatest champions last contested a professional tennis match, but a different kind of shot has stripped 31lb (2.2 stone) from her frame in retirement.
From rooftops to breakfast show couches, Williams has been on a mission to explain how, but nowhere is the messaging more pronounced than on the website for an American telehealth giant, Ro, where her husband, the Reddit co-founder Alexis Ohanian, happens to be an investor.
It’s one of their products that she has been advertising, so we can assume the caption that accompanied the picture was approved: ‘Serena’s on Ro. Are you next?’
‘On’ is a loaded word in sport, especially if there’s a needle in the frame, but for 23-time Grand Slam winner Williams there is no case to answer. Even if she was still competing in elite sport, the prime ingredients that go into Ozempic, Mounjaro, Wegovy, Zepbound and different brands of the same concept that has been the talk of the weight-loss world for the last two years are not yet banned in elite sport.
Serena Williams faced a backlash for front an advertising campaign by Ro, a weight-loss jab
Williams’ husband, the Reddit co-founder and Chelsea Women part-owner Alexis Ohanian (right), is an investor in Ro
But the question of ‘who comes next’ is a subject of deep intrigue within anti-doping authorities.
We have already seen ex-athletes among the tens of millions who have used the jabs – including Williams, the former Olympic champion Carl Lewis, Billie Jean King and the NBA icon Charles Barkley – but what about those still in the field? Is another biological frontier opening in sport?
Daily Mail Sport has spoken to more than a dozen sources to explore this issue, from leading doping investigators and professors to athletes, nutritionists and coaches.
We have also heard the fears of a senior figure in horse racing and, furthermore, obtained a confidential document compiled by the World Anti-Doping Agency (WADA) that shows the active ingredient in those jabs appeared in drug tests in two other sports last year.
It remains to be seen whether a threshold will be crossed that leads to them being prohibited in professional sport – the discussions are ongoing.
But for now there is at least a consensus and a health warning for any top-level athlete tempted to adopt this measure: it might do far more harm than good.
The sporting concerns in this area are valid. Those were best illustrated by a decision last year from WADA, who took the step of including semaglutide, the active ingredient in Ozempic and Wegovy, on their ‘monitoring list’.
For that to escalate to a banned status, WADA’s protocol dictates two of three boxes would need to be ticked: could a substance enhance performance; is it a health risk; does it violate the spirit of sport?
NBA legend Charles Barkley lost 4.5 stone in just six months by taking Mounjaro injections
‘We are not there yet,’ says Professor Olivier Rabin, WADA’s head of science, who expects their study to be extended into 2026 and also indicated to us that tirzepatide, sold as Mounjaro and Zepbound, has joined semaglutide under the microscope for observation.
Both substances are known scientifically as ‘GLP-1 agonists’ and have proven effective at suppressing appetite and slowing digestion. Their appeal to the wider population in the past few years has been immense – more than 500,000 people are taking some form of weekly weight-loss injection in the UK, including Boris Johnson, Robbie Williams and James Corden. A poll of American adults last year found that one in eight have taken one at some stage in their life, or around 35million people.
The reasons why these methods might tempt athletes in weight-control sports, or those placing a premium on aesthetics like gymnastics, seems obvious from the outside.
‘We’ve seen a few athletes reporting in the media, sometimes on social media, the use of those substances, but usually they are no particular concern because they are not necessarily elite athletes,’ adds Professor Rabin. ‘Of course, some athletes would be tempted. This is why we are concerned about risk of abuse.’
Currently, the evidence is largely anecdotal and predominantly the preserve of recreational sport – the use of weight-loss drugs among amateur runners, triathletes and cyclists is known.
Outside of Stuart Bingham, the 2015 snooker world champion, and occasional, unsubstantiated reports about the boxer Andy Ruiz, who has undergone a startling body transformation in the past year, no leading sportsman or woman has said publicly that they are using the medications, which are prescription-only.
But since WADA revised its monitoring list in 2024, a trickle of harder data has emerged.
One document they circulated to stakeholders on July 11 of this year, and seen by Daily Mail Sport, disclosed that semaglutide was monitored in 8,402 out-of-competition urine samples, with two positive findings for metabolites common to semaglutide and tirzepatide. One of those came from cycling and the other from rugby league.
The 2015 world snooker champion Stuart Bingham lost three stone from weekly weight-loss jabs, which he began late last year
Rabin confirmed the veracity of the report, but adds that such a tiny number would fall far short of a threshold. WADA would instead need to see more established patterns, including multiple finds from the same team or a particular sport to suggest a targeted use of the medications.
The curiosity is shared by the US Anti-Doping Agency. ‘I think when you’re looking at emerging drugs like this that have been become blockbuster drugs, then there is obviously a concern,’ says Dr Matthew Fedoruk, their chief science officer.
‘I think it’s only natural to say, “Okay, let’s take it a step further here and really understand whether there’s a potential for abuse”. The jury is still out on whether we fully understand its use.
‘I think right now, we’re hearing at the recreational level, but not at the elite. That being said, we see in the past that trends that start appearing in the recreational level have a tendency to be abused at the elite level as well.’
The performance risks attached to doing so take us to a different question – why would an athlete bother?
Studies have shown semaglutide can cause a loss of lean muscle by as much as 10 per cent. Other side effects can include vomiting, nausea, dizziness, blurred vision and diarrhoea. None of these, you will note, are ideal in top-level sport.
‘Looking at the side effects, they may outweigh the benefits, if I may use this pun,’ says Professor Rabin.
Greg Whyte, a professor of applied sport and exercise at Liverpool John Moores University and a former Team GB Olympian, goes further. He told Daily Mail Sport: ‘We can all see why, on the surface, someone would be tempted, but it would be a very bad idea.
Weight-loss drugs might look like a good idea to those on the outside of professional sport, but they would come with severe risks for athletes
‘Based on the muscle loss that we have seen reported, it’s the antithesis of what you are trying to achieve. Athletes with a competent team around them will know this, and others would need to get educated about it.
‘There are a lot of sports where weight management is critically important. In horse racing, judo, boxing, or anything that’s got a weight-making class to it, you might have to operate within a very narrow band around a weight category and in some situations it requires weight loss quite quickly to make a limit.
‘GLP-1 agonists might seem like they work quickly in the general population, but not in elite sport – the weight won’t come off in the timeframes they tend to work to in those scenarios (ie. the few days before a boxer’s weigh-in).
‘Even if the argument is that you’re going to use it in the longer term, it wouldn’t make any sense at all – it is an appetite suppressor and that means you’re not fuelling enough for training and therefore the quality of the session will drop.
‘On top of that, because you’re under-nourished, the recovery process will be slowed. Effectively, everything about GLP-1 points in the opposite direction to what you’re trying to achieve as an elite athlete.’
All of that being said, sources in boxing have cryptically floated the possibility of fighters using the substances as a headstart prior to going into camp for a bout. Once there, the calorific intake needed to get fight-ready would make an appetite suppressant illogical, given they might need to burn anywhere between 2,000 and 4,000 calories per day to achieve effective training and not strip away muscle while making weight.
‘To anyone informed in elite sport, it would be a no-brainer not to take it,’ Whyte adds. ‘Obviously it sounds like Harry Potter’s magic wand, but it’s not what an athlete needs.’
The issue, as ever in the thorny turf of substances and applications for which they were never intended, is less to do with the present and more the future.
Andy Ruiz Jnr, the conqueror of Anthony Joshua in 2019, was targeted by baseless rumours that he had taken weight-loss jabs
US Anti-Doping and WADA are both alert to the possibility that Ozempic, for instance, could see a spike in its appeal to athletes if the muscle-loss element is mitigated, which is possible by taking it alongside other substances.
‘What is interesting to my perspective is drug companies are recognising this side-effect (muscle loss),’ says Dr Fedoruk. ‘One of the things that we’re particularly interested in is these clinical trials that are happening where you’ve got synergistic effects of, say, using semaglutide and pairing it with a prohibited substance, like a selected androgen receptor modulator, and you actually prevent that muscle loss by up to 70 per cent.
‘There is the potential for an athlete to say, “Listen, maybe I roll the dice here. I don’t think I’m going to be tested”. I think we need to keep a close eye on that aspect of it. We always have to stay ahead of the game.’
Naturally, the need in some games will be stronger than others. For that reason, several of our conversations touched on horse racing.
The scientific logic follows that combat sports require too many calories to risk suppressing appetite, especially when the jabs are too slow-acting to assist in those desperate days before a weigh-in.
It was also considered unsuitable for similar reasons in cycling and gymnastics by our sources.
A potential outlier involves racing. Unlike the ebbs and flows of a boxer in the lighter categories, jockeys are forced to keep below their natural weight for much of the year. Their calorific expenditure is also less – one study found they might burn 2,500 calories across six rides in a day, which is surprisingly low.
Given those factors, added to relentless travel, injuries and the closure of trackside saunas since Covid, the appeal of a shortcut to alleviate a constant hunger is self-explanatory. To its credit, the racing industry recognises as much.
The jockeys’ weight room at Newmarket. Racing chiefs have admitted they have to be alive to the threat of weight-loss jabs entering their sport
Paul Struthers, the CEO of the Professional Jockeys Association, told me: ‘It’s obviously something we’re acutely alive to because it’s in the press every day.
‘The fact is that almost all of our jockeys on that are maintaining a weight that is unnatural.
‘When there’s something that might just make it easier, then we’re alive to those possibilities.’
Along with several jockeys and trainers interviewed for this article, Struthers says he has never directly heard of the measure being taken, but adds: ‘We have approximately 380 professional jockeys in this country – I’m not naive, so I wouldn’t be surprised if there have been one or two that have thought, “Oh, I’ll give that a go”. We are keeping a very close eye on it.
‘We are trying to educate them, because they’re obviously not obese and they don’t have diabetes, which is what these GLP-1 substances are designed for. It’s unlikely to have a beneficial effect and will come with potentially serious side effects.’
The question is whether the risks are deemed to be worth it over other weight-loss methods, which have included vomiting after meals. Some have even linked cocaine use to attempts to lighten loads.
The former Derby winner Adam Kirby, who himself retired earlier this year after constant battles against the scales, is more aware than most of the challenges.
‘I haven’t heard of anyone using the sticky tummy pen thing,’ he says. ‘I remember once hearing talk of a couple of jockeys having gastric bands. I don’t know if anyone followed through with it, but it is a hard life.
Adam Kirby, who won the Derby in 2021, insists it would make no sense for jockeys to take a weight-loss jab
‘What I always say is, using things like that, where there’s an up, there must be a down. I think it would make no sense at all to have those injections.
‘When you’re a jockey, you’ve got to be on the ball. It’s like being a racecar driver, everything happens very, very quick.
‘You need your leg muscles, you need your lungs to be wide open, and you need to be fit. You don’t mess with that.’
It seems like a sensible take and a warning that ought to apply across the world of sport, irrespective of whether Harry Potter’s magic wand is one day banned from our games.
