A new ‘Godzilla’ weight‑loss jab could help tackle arthritis, heart disease and sleep apnoea – while also driving dramatic slimming, a major trial suggests.
Researchers found retatrutide helped 45 per cent of patients lose at least 30 per cent of their body weight, with some achieving results close to those seen with bariatric surgery.
But scientists say the drug’s impact goes far beyond weight loss.
As well as helping patients shed pounds, the treatment improved blood sugar control, reduced cardiovascular risk factors and cut knee osteoarthritis pain by around 70 per cent.
It also showed potential to ease sleep apnoea, underlining its ability to tackle multiple serious conditions linked to obesity.
Professor Ania Jastreboff, of Yale School of Medicine and lead investigator on the trial, said: ‘Obesity is a chronic disease, and people living with obesity deserve treatment options that match the complex biology of their condition.
‘Importantly, treatment with retatrutide not only resulted in robust weight loss, but also clear improvements in cardiometabolic health.’
She added: ‘People with severe obesity on the highest dose lost on average around 30 per cent of their body weight.’
Retatrutide, known as the ‘Godzilla jab’, is the most powerful GLP-1 ever developed, but is not yet licensed and cannot be legally dispensed by a pharmacy
Experts say the findings mark a shift towards drugs that can treat both obesity and its complications in one.
The results come from the TRIUMPH‑1 trial, which involved more than 2,300 participants and was presented at the American Diabetes Association’s 2026 Scientific Sessions.
Patients lost up to around 30 per cent of their body weight – roughly 70lbs (32kg) on average over the course of the study.
Currently, the most powerful licensed weight‑loss jab, Mounjaro, helps users lose around 20.9 per cent of their body weight over 72 weeks.
Both drugs are made by US pharmaceutical giant Eli Lilly, which is expected to seek approval to roll out retatrutide in the UK within months.
Retatrutide – nicknamed ‘Godzilla’, ‘reta’ and ‘triple G’ – works as a triple‑agonist, targeting three hormone receptors linked to appetite, metabolism and energy burn.
While earlier weight‑loss jabs have largely focused on suppressing appetite, this drug also boosts the body’s calorie‑burning processes, helping explain its wider health effects.
Dr Simon Cork, of Anglia Ruskin University, said: ‘These results are incredibly promising and show we are moving closer to being able to effectively treat obesity with medication.
‘The improvements in wider health measures are particularly encouraging.’
However, experts warn that the treatment is still experimental, with common side effects including nausea, diarrhoea and vomiting and more research is needed to confirm its long‑term safety.
Last week, Dr Luke Turnock, a senior lecturer in criminology at the University of Lincoln in the UK who monitors illegal drug sales, told the Daily Mail that retatrutide was the most listed GLP-1 on the illicit market back in 2024 – and its popularity is growing alarmingly fast.
Dr Turnock worked closely with fellow scientist Dr Luke Cox, a lecturer from the school of sport and exercise science at Swansea University, on a study published in April this year highlighting the crucial role played by social media and internet forums in boosting a false sense of confidence around fake reta.
There is a ‘reliance on anecdotal expertise’, said Dr Cox, which encourages the ‘spread of misinformation, unsafe experimentation and exaggerated claims of efficacy’.
His great concern is that social media influencers – funded by incentive payments through affiliate links to online shops – are expanding the popularity and perceived ‘safeness’ of reta into the mainstream.
‘The rapid expansion of this market is scary,’ says Dr Cox. ‘It’s like the Wild West.’
