Weight loss drugs trigger significant muscle-loss – including in the face – according to a major new study.
The injections, Mounjaro and Wegovy, are taken by more than 2.5million people in the UK.
Previous research has found that obese patients can lose up to a fifth of their body weight on the jabs.
But a new report, which reviewed the health data of thousands of patients taking the drugs, found that two-thirds of users also lost crucial muscle mass.
Experts say this muscle-loss is almost certainly to blame for the phenomenon known as ‘Ozempic-face’ – where weight loss jab users’ faces appear hollowed out, with visible cheekbones.
In 2024, reality TV star Sharon Osbourne said that, after taking weight loss drugs she felt ‘too gaunt’ and ‘too skinny’, as well as admitting she was struggling to put weight back on.
The researchers behind the new review, which will be presented at the American College of Physicians’ Internal Medicine Meeting, San Francisco, are now warning users to take steps to avoid muscle-loss, which can lead to life-threatening complications, including life-threatening falls.
Dr Charlotte Suetta, a geriatric consultant at Copenhagen University Hospital, commenting on the study, said: ‘Treatment should be paired with strategies likely to preserve muscle health, especially resistance exercise and adequate protein intake.’
Sharon Osbourne pictured in 2024; the former X-Factor judge, 73, has been frank about how her use of weight loss drugs had left her ‘too gaunt’
Reviewing 36 weight loss drug studies, the researchers found that patients always lost more muscle than anticipated.
It comes following a landmark Oxford study, published in January, that found the majority of users pile the pounds back on within two years of stopping treatment, much faster than traditional dieters.
At the time, experts warned that stopping the drugs does not just reverse weight loss, but is also linked to a reversal of key heart benefits.
The jabs, known collectively as GLP-1 drugs, work by mimicking hormones released after eating.
But experts have raised concerns about what happens when users come off the jabs, insisting that those being prescribed the medications should receive advice about diet, nutrition and increasing physical activity – which can help preserve muscle mass – alongside the jabs.
Anecdotally, whilst many credit the jabs with helping them lose weight quickly, others have noticed loose skin on their cheeks and neck, leading to a phenomenon dubbed as Ozempic face.
When someone gains weight, their skin adapts and stretches, but when they lose weight – and muscle which helps to tone the face and body- their skin can remain stretched.
And its thought the more rapid the weight loss, the more extreme the effect.
Robbie Williams was among the earliest male celebrities to admit to using GLP–1s after the pop star now famously told The Times he was diagnosed with ‘type 2 self–loathing’
Meghan Trainor admitted last year to using Mounjaro to help her shed a substantial amount of wieight
‘The aesthetic change often referred to as ‘Ozempic face’ is typically linked to the pace and composition of weight loss, rather than the medication itself,’ says Dr Ruby Aktar, a neuroscientist and weight-loss expert at Queen Mary University of London.
‘When weight is lost quickly, the body doesn’t just draw from fat stores, it can also break down lean muscle and the structural fat that supports areas like the face.’
In some cases, this weight-loss can leave users not only looking gaunt and malnourished, but at serious risk of frailty and falls as they rapidly lose not just fat but bone and muscle mass.
Dr Suetta warned that for this reason, weight loss jabs may not be always be appropriate for older adults looking to lose weight.
She said: ‘In older adults, preservation of muscle may be decisive for whether weight loss leads to better health or greater vulnerability.
‘For older adults especially, this is not just about body composition.
‘It is about mobility, falls, frailty, and the ability to maintain an independent life.’
Experts have long advised that strength training can help users maintain muscle mass while on the jabs and after coming off them.
But in the absence of specific research on the best training protocols for maintaining muscle mass whilst losing weight, the authors suggest users should stick to national guidelines – which recommend 150 minutes of moderate to vigorous exercise a week.
Meghan Trainor, 31, is just one of the many celebrities who have admitted to using the jabs.
But for the singer it wasn’t just about losing weight, but making ‘huge lifestyle changes’ which saw her work with a dietician and personal trainer to slim down and manage her diabetes.
It comes as the National Institute for Health and Care Excellence (NICE) announced this month that more than a million people with heart disease will be offered the injections on the NHS.
The decision marks the first time the drugs have been approved in the UK specifically to prevent heart problems, rather than simply for weight loss.
Until now, medicines such as Wegovy and Ozempic have been used mainly for obesity and diabetes.
Two in three Britons are now classed as overweight or obese, while NHS figures show adults weigh roughly a stone more than they did 30 years ago – a trend estimated to cost the economy £100 billion a year.
The arrival of GLP-1 drugs has transformed obesity treatment, offering dramatic weight loss that was largely out of reach with diet and exercise alone.
Concerns have been raised about the risks of the medicines, which can cause nausea, vomiting and diarrhoea, and in rare cases have been linked to pancreatitis, but experts say the benefits far outweigh the risks for most patients.
