The new generation of weight-loss drugs has changed the conversation around obesity. Medications such as Ozempic, Wegovy and Mounjaro have delivered something that decades of dieting never quite managed: consistent, significant weight loss for large numbers of people.
But beneath the headlines and celebrity endorsements lies a quieter, less comfortable truth – one that’s now being backed by solid evidence.
For many people, the weight comes back when the drugs stop.
And that’s not a failure of willpower. It’s biology.
What the Research Shows
A major review led by researchers at the University of Oxford examined 37 clinical trials involving more than 9,000 participants who had taken GLP-1 weight-loss drugs. The finding was striking: most people began regaining weight soon after stopping the medication, at an average rate of about 0.4 kilograms per month.
Within 18 to 24 months, many had regained a substantial portion – and in some cases nearly all – of the weight they had lost.
Lead researcher Dr Sam West said even the research team was surprised by the speed of the rebound.
“We know that weight regain is common after people lose weight, but we were surprised at how quickly people regained the weight after stopping medication,” he said.
“This isn’t a failing of the medicines – it reflects the nature of obesity as a chronic, relapsing condition.”
Importantly, the study found that weight regain after stopping medication was faster than what’s typically seen after ending diet-and-exercise programmes.
Why the Weight Returns
To understand why this happens, it helps to understand how the drugs work.
GLP-1 medications don’t burn fat directly. They alter appetite signals, slow stomach emptying and reduce hunger. While you’re taking them, the brain receives fewer signals to eat – and weight loss follows.
But when the medication stops, those signals return.
Professor Giles Yeo, a leading obesity researcher at the University of Cambridge, puts it bluntly:
“Like most drugs – with the exception of vaccines – they typically only work when you’re on them,” he says.
“When your blood pressure is normalised, no one ever says, ‘I’m going to stop taking my pill.’ Because what happens if you stop is, almost immediately, your blood pressure becomes abnormal again. The same is going to be true for these weight-loss drugs.”
In other words, the drugs manage obesity – they don’t cure it.
Obesity as a Chronic Condition
This is where thinking around weight loss is beginning to shift.
For decades, obesity was framed as a lifestyle issue – something you could “fix” with enough discipline. But growing scientific consensus now treats obesity more like diabetes or hypertension: a chronic metabolic condition that often requires ongoing management.
Dr Flávio Mitidieri Ramos, an obesity medicine specialist, explains it this way: “Stopping GLP-1 medications often reveals something we don’t talk about enough: the drug was doing part of the physiological work that lifestyle alone may not yet be prepared to sustain,” he says.
“Weight regain is not a personal failure; it is a predictable biological response.”
That perspective matters – especially for people who feel ashamed or discouraged when weight returns after stopping medication.
Does This Mean You’ll Need Them Forever?
For many people, the answer may be yes.
That doesn’t mean everyone must take these drugs indefinitely. Some people do maintain part of their weight loss, particularly when they’ve made lasting changes to diet, movement and routine. But the dominant pattern in the data is that stopping medication often leads to regain.
Dr West is careful to emphasise that this shouldn’t be seen as a flaw.
“These medicines are transforming obesity treatment and can achieve important weight loss,” he says.
“But our analysis shows people tend to regain weight rapidly after stopping – faster than after ending behavioural programs.”
That reality raises difficult questions about cost, access and long-term prescribing – especially as more people begin these treatments later in life.
A Shift in Expectations
The real adjustment may not be medical, but psychological.
If we accept that weight-loss drugs function more like cholesterol or blood-pressure medication – effective while taken, less so when stopped – then expectations need to change. The goal becomes management, not cure.
For people in their 50s, 60s and beyond, that may actually be liberating. It reframes weight regain not as a moral failure, but as the natural outcome of a complex biological system returning to its default state.
The Bottom Line
These drugs are powerful. They work. For many people, they improve health, mobility and quality of life.
But the evidence is increasingly clear: they are not a short-term fix.
As with many chronic conditions, the benefits last only as long as the treatment continues. And that may be the hardest truth of all — not because the drugs fail, but because our expectations of weight loss have been unrealistic for far too long.
IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.