Quick answer: A major new study found that people typically regain lost weight within 1.5–2 years of stopping GLP-1 drugs like Wegovy or Mounjaro — four times faster than after lifestyle-only weight loss. The medications are genuinely effective, but lasting results come from building sustainable habits (especially resistance training) alongside them, not from the drug alone.
The start of a new year is often when people feel most motivated to make changes. Exercise more. Eat better. Lose weight. And yet, year after year, many of us find that good intentions don’t always translate into lasting change. One of the reasons this interests me so much is that behaviour change is rarely about willpower alone. Willpower is powerful — but it’s also finite. What really drives long-term success is the quiet accumulation of small, repeatable habits that become part of daily life. Over the past few weeks I’ve written about New Year’s resolutions and why many of them fail. One of the most common resolutions, unsurprisingly, is weight loss. And right now, weight-loss medications — particularly the GLP-1 agonists — are dominating the conversation in the media. I haven’t actually written about them for months now, but given I’ve received quite a few questions on this topic recently I thought it a good time to give an update.
Do GLP-1 drugs really work?
There’s no question that medications such as semaglutide (Wegovy) and tirzepatide (Mounjaro) are highly effective. I’ve been prescribing them for well over a year now, and in the right patients the results can be genuinely transformative.
They can reduce appetite and food noise; enable meaningful fat loss; Improve blood sugar, blood pressure, and cholesterol; give people the confidence and physical capacity to exercise again. For patients who have struggled for years — sometimes decades — these drugs can offer hope and momentum where little existed before. But they are not a magic bullet!
What happens when people stop taking them?
And that brings us to a new study that has been widely reported in the press, and speaks to the often asked question: What happens when people stop GLP-1 drugs? A large new meta-analysis published in The British Medical Journal examined what happens after weight-loss medications are stopped. The headline finding was stark: On average, people returned to their baseline weight within about 1.5–2 years after stopping treatment. Weight regain occurred four times faster than after lifestyle-only interventions. Cardiometabolic benefits (blood sugar, cholesterol, blood pressure) also faded rapidly. At first glance then, it’s understandable that headlines like this might make people think “What’s the point, if the weight just comes back?” But that would be an oversimplification — and, in my view, the wrong conclusion.
Why does weight regain happen?
So why does weight regain, and why might that outcome not be inevitable? Obesity is increasingly recognised as a chronic, relapsing condition, not a personal failure. When we remove a treatment that suppresses appetite and improves metabolic signalling, it’s unsurprising that weight regain can occur — particularly if nothing else has changed. One of the most telling observations from the study was that regain was fastest when people relied solely on the medication to do the heavy lifting. This mirrors what I see in clinical practice. In my experience, people are far more likely to keep weight off when:
Weight loss is gradual, not rapid
Lower or moderate doses are used over longer periods
Exercise — especially resistance training — is prioritised
The focus is on fat loss, not just “weight”
Habits are deliberately built while the medication is supporting appetite control.
Why fat loss matters more than the number on the scale
When people say they want to lose weight, what they usually mean is that they want to lose fat — while preserving muscle, bone health, and strength. That’s particularly true for many female patients, especially per–menopausal or post-menopausal when oestrogen levels plummet without treatment, fat distribution changes, and without due care bone health can really suffer. This is why I place such emphasis on exercise during treatment, especially resistance training. Losing muscle mass may lower the number on the scales, but it undermines long-term health and makes weight regain more likely.
Often people say to me things along the lines of ‘it’s ok for you, you’re slim’. What this simple sentence misses is the lengths I go to in my own life to stay this way. I guarantee if I ate badly and didn’t exercise I would get fat and unfit. I do totally accept I enjoy exercise, which definitely helps, but there are still plenty of times when I don’t feel like it but have that habit deeply engrained to prompt me to do the work. But, no one — myself included — gets this right all the time. Something that helps me a lot mentally with my healthy habits is my rule: “Never miss twice”.
I have days when I don’t exercise. Days when nutrition isn’t ideal. Days when motivation dips. When those days happen, and they will every week, one of the simplest strategies I use is what I call the “never miss twice” rule: If I skip a workout one day, that’s allowed. Skipping two days in a row isn’t. The same applies to other habits — including my cold showers. Miss one day, fine. Miss two, not allowed. This approach removes guilt, but preserves momentum. And momentum is everything when it comes to behaviour change.
Some patients have told me they’ve decided not to start weight-loss medication because they’re worried they’ll just regain the weight later. That’s understandable — but it’s not the whole story. In practice: many patients do maintain their weight loss after stopping, others may need to restart treatment — and that’s not a failure. I would much rather see someone on a low dose for longer, with sustainable habits, than chase rapid weight loss on high doses. In fact, in my own practice, the vast majority of patients are on less than a third of the maximum dose. Used thoughtfully, these medications can be a powerful adjunct to lifestyle change — not a replacement for it. Remember there are big upsides to the medications too – for example lowering heart attack and stroke risk, and treating heart failure.
One of the things patients often tell me is that simply tuning in each week — to my blog, a research video, or an update — gives them a small but meaningful nudge to stay on track. Not perfection. Just direction. And that matters, because none of us live perfectly. Long-term health isn’t about never slipping — it’s about how quickly you get back on course. Behaviour change genuinely fascinates me. It underpins how I practise medicine and why I find this work so fulfilling. Seeing people regain confidence, strength, and control over their health is deeply rewarding.
I don’t dismiss GLP-1 drugs, despite the recent headlines. Weight-loss medications should neither be dismissed nor oversold. They are tools — powerful ones — and like all tools, they work best when used properly, for the right person, at the right time, alongside the right foundations. If you’re interested in learning more, or want to explore your options in a safe, evidence-based way, I’m always happy to help — within the appropriate UK regulatory framework.
And remember: You don’t have to be perfect. You just have to not miss twice.