It is easy to underestimate how dramatically obesity treatment has changed. Just five years ago, there was no genuinely effective medical treatment for obesity. Doctors could recommend healthier eating and more exercise, but for many patients those measures alone failed to produce lasting results.
Then came the weight-loss injections: Ozempic, Wegovy and Mounjaro. Together, they reshaped the field.
At last, patients had access to treatments capable of producing significant weight loss and, importantly, helping them maintain it for as long as they continued taking the medication.
The advances have continued. This year, the first tablets from a new generation of weight-loss treatments began to emerge, offering a potential alternative for people who are uncomfortable with injections.
It is a treatment landscape I could hardly have imagined only a few years ago.
For decades, obesity was exceptionally difficult to manage. Even patients who worked tirelessly to lose weight often found that it eventually returned.
Now, for the first time, we have medicines collectively known as GLP-1s that can alter that pattern.
The next major development may already be on the horizon: retatrutide.
As weight falls, the body adapts by burning fewer calories, making continued loss increasingly difficult. Retatrutide’s effect on glucagon could help to counter that response
The experimental drug is still being tested in clinical trials, but its strength has already earned it the nickname ‘Godzilla’ among weight-loss injections. Early findings suggest it could help people lose almost a third of their body weight.
Retatrutide is not yet available in the UK. Yet demand is already so high that thousands of Britons are buying illegal versions, sometimes with devastating results, as I will explain later.
That has given the drug a controversial reputation. Doctors are understandably wary when patients say they are injecting an unlicensed medicine. I share those concerns.
Even so, I believe retatrutide, known online as ‘Reta’, could transform the lives of many people. That may include patients who have not responded adequately to Wegovy or Mounjaro, as well as those whose weight loss has stalled after an initially successful start. Doctors refer to this as the ‘GLP-1 plateau’.
I work as a GP in both the NHS and private practice, specialising in obesity, and have prescribed weight-loss injections for three years. During that time, I have treated around 20,000 patients, giving me a clear sense of what works and where the limitations lie. Many are already asking me about Reta.
Most are women aged between 35 and 60 who have been taking the highest 15mg dose of Mounjaro for at least a year. They have lost a substantial amount of weight, but the scales have stopped shifting, and many remain obese.
Some have lost one stone despite hoping to lose two. For a smaller group, the medicines have made very little difference. This can be particularly upsetting for women in the perimenopause or menopause, when hormonal changes may make weight management more challenging. These are the patients who, in my view, could potentially gain the most from retatrutide.
Obesity was extraordinarily difficult to treat for decades. Today, medicines known collectively as GLP-1s are offering patients a new possibility
That does not mean retatrutide will be suitable for everyone. There are several important points to consider.
To understand its potential, it helps to know how the drug differs from existing treatments. Wegovy imitates the gut hormone GLP-1, which helps suppress appetite. Mounjaro acts on GLP-1 and a second hormone, GIP, producing a stronger effect. Retatrutide targets both of those pathways and adds a third hormone, glucagon, which may increase the amount of energy the body uses while also reducing food intake.
The trial results have been striking. In research published in May involving more than 2,300 adults, participants receiving the highest dose lost around 28 per cent of their body weight over 80 weeks. For someone who began at 18 stone, that would be roughly equivalent to losing five stone.
By comparison, people taking Wegovy typically lose about 15 per cent of their body weight, while those using Mounjaro lose around 20 per cent.
That represents a remarkable step forward. The question my patients ask most often is whether retatrutide could help them move beyond the weight-loss plateau.
There are encouraging reasons to believe it may.
After weight loss, the body adapts by using fewer calories, which makes further progress harder. Retatrutide’s action on glucagon could help offset some of that metabolic response.
Crucially, trial participants taking retatrutide showed little evidence that their weight loss was slowing, even after 80 weeks of treatment.
For people who have reached a plateau, the treatment cannot arrive soon enough. Many have struggled with their weight for years and believed these injections would finally provide the answer. They have watched celebrities and social-media influencers undergo dramatic transformations and spent thousands on treatment, only to see their own results fall well short.
When retatrutide is approved, these are the patients I would consider for treatment, along with people who have a particularly large amount of weight to lose.
One of my patients has lost six stone, a change that has transformed her life. Yet she remains obese and still faces a higher risk of heart disease and some cancers. It is understandable that she asks why other people have lost so much more. For someone in her position, retatrutide could prove significant.
There are, however, good reasons for caution. In the trial, one-quarter of participants taking the highest dose experienced vomiting, while more than four in ten reported nausea. Around one in nine people on that dose stopped treatment because of side effects.
I already see patients experiencing vomiting with existing injections. If you only want to lose a few pounds, this is certainly not the treatment for you.
GP Dr Saira Bano believes retatrutide, or Reta, could transform the lives of many people who have not responded to Wegovy or Mounjaro
I would also strongly advise people to stay away from the black market. Retatrutide has not been approved anywhere in the world, and British factories producing counterfeit injection pens have already been raided.
Many NHS patients tell me they are using retatrutide. In one case, the person had actually been injecting insulin, a diabetes treatment, instead.
I expect retatrutide to become available towards the end of next year. Once approved, patients will begin on a low dose, which will be increased gradually, following the same general approach used with Mounjaro and Wegovy.
The familiar advice will still apply. These medicines are not magic wands. Patients need to eat well and exercise regularly to preserve muscle and improve their chances of keeping the weight off.
Without those changes, even the most advanced weight-loss medicine may deliver disappointing results.
A drug can reduce hunger, but the habits developed alongside it are what ultimately determine whether the benefits endure.
When retatrutide eventually arrives, I expect to prescribe it to many of my patients. If the early evidence is confirmed, some of the results could be remarkable.
