Semaglutide is the weight-loss drug everyone has heard of. You probably know it as Wegovy, or its diabetes cousin, Ozempic.
In trials, it works remarkably well. In the big STEP 1 trial, people lost about 15% of their body weight on average.
But there's a catch the trials can't show you. What happens when real people, paying real money, try to stay on it?
A new study from Denmark has the answer. And it's a bit of a shock.
About half of the people who started semaglutide for weight loss had stopped within a year.
- Half of the people who started semaglutide for weight loss in Denmark stopped within 12 months.
- Younger adults and men were the most likely to stop, but no group stayed on reliably.
- Earlier research shows that the weight tends to come back after stopping, so this matters for anyone considering the drug.
The study: every new user in a country
How it worked
Researchers at Aarhus University in Denmark used the country's national health registries. These record every prescription filled at a pharmacy.
They found every adult who started semaglutide for obesity between December 2022 and November 2024. People with diabetes, and anyone who had used semaglutide before, were left out.
That gave them 157,822 people. Most were women (69%), and the typical user was 49 years old.
This is the study's big strength. It isn't a selected group of volunteers.
It's essentially everyone in the country who started the drug.
How "stopping" was defined
Nobody asked people whether they had stopped. Instead, the researchers followed the prescriptions.
If someone's supply ran out and they then went 60 days without a refill, they counted as having stopped.
They also tested stricter and looser versions, with gaps of 30 days and 90 days. That's a useful check, because the answer could change a lot depending on the rule.
Half had stopped within a year
Here's the headline result. Of the 157,822 people who started, 77,483 had stopped within 12 months.
That's 49%.
And the stopping started early. Here's how it built up over the year.
| Time after starting | Share who had stopped |
|---|---|
| 3 months | 13% |
| 6 months | 27% |
| 9 months | 39% |
| 12 months | 49% |
The definition mattered, but not enough to change the story.
With a 30-day gap, 58% had stopped. With a 90-day gap, 45% had.
However you slice it, somewhere around half of people didn't stay on the drug for a full year.
Stopping, then starting again
There's an important twist. About 1 in 4 of the people who stopped started semaglutide again within 3 months.
The researchers think some of this reflects breaks in treatment. People might pause for a while, or stretch their doses to make supplies last.
So "stopped" doesn't always mean "gave up for good". It can mean on-and-off use.
Very few switched to a rival drug.
Only 1.4% filled a prescription for liraglutide, an older drug in the same family. And 0.7% moved to tirzepatide (sold as Mounjaro or Zepbound), which only reached Danish pharmacies in late 2024.
Who was most likely to stop?
The researchers compared different groups, adjusting for age and sex. Here are the clearest differences.
| Group | Compared with | How much more likely to stop |
|---|---|---|
| Aged 18 to 29 | Aged 45 to 59 | 49% more likely |
| Men | Women | 16% more likely |
| Living in a low-income area | Living in a high-income area | 11% more likely |
| Had used psychiatric medicines before | Hadn't | 13% more likely |
| Had used stomach or gut medicines before | Hadn't | 10% more likely |
People with more health problems, such as heart disease or kidney disease, were also slightly more likely to stop.
But here's the part I find most striking. In every single group, at least 41% stopped.
No type of person reliably stayed on the drug. The differences were real, but they were differences between "a lot" and "a bit more".
In Denmark, about half of the people who started semaglutide for weight loss stopped within a year. Young adults and men stopped most often, but every group had a high dropout rate.
Why do people stop?
This study can't say for sure. The registries record prescriptions, not reasons.
But the authors point to two likely culprits.
Money
In Denmark, semaglutide for weight loss isn't covered by the public health system. People pay the full price themselves.
That's roughly €2,200 to €3,700 a year (about US$2,500 to US$4,200), depending on the dose.
The link with lower-income areas fits this. So does the higher dropout in young adults, who often earn less.
Side effects
Nausea, vomiting and other stomach problems are common on semaglutide.
People who had already needed medicines for their gut were a bit more likely to stop. The authors suggest they might be more sensitive to these side effects.
The link with earlier psychiatric medicines is harder to read. It might reflect a general difficulty sticking with long-term medicines.
What earlier research found
This isn't the first sign that people struggle to stay on these drugs. And earlier research also tells us what tends to happen next.
Cost is the top reason in the US too
A 2025 study from a large US health system looked at medical records to find out why people stopped. It randomly picked 288 adults who had stopped semaglutide or tirzepatide within their first year.
Cost or insurance problems were the main reason for 47.6% of them.
Side effects came next, at 14.6%. Drug shortages accounted for 11.8%.
Only 1.7% stopped because they weren't losing enough weight.
Stopping early means losing less
The same US team followed 7,881 people who started semaglutide or tirzepatide for a year.
People who stayed on the drug lost 11.9% of their weight on average.
Those who stopped within 3 months lost only 3.6%. Those who stopped later lost 6.8%.
That's well below the results from the big trials. The researchers put it down to people stopping and staying on lower doses.
The weight tends to come back
What happens after stopping? The STEP 1 trial tested this directly.
People took semaglutide for 68 weeks and then stopped. A year later, the trial's extension found they had regained about two-thirds of the weight they'd lost.
Improvements in blood pressure, blood sugar and cholesterol mostly faded back towards where they started too.
A 2026 review in The BMJ pooled 37 studies with 9,341 people who stopped weight-loss medicines. On average, people regained about 0.4 kg (roughly 1 pound) a month after stopping.
Heart and metabolism markers were projected to return to where they started within about 1.4 years. Weight also came back faster than after stopping a diet-and-exercise programme.
How it fits together
Put these together, and a clear picture emerges.
Semaglutide works while you take it, and the weight tends to return when you stop.
In the real world, about half of people stop within a year, often for reasons like cost.
That's the gap this Danish study measures so clearly. It's the difference between how well a drug works and how long people stay on it.
How much should you trust this?
Strong, for the main number. This is a complete national dataset, not a sample, and the result held up under different definitions of stopping.
What makes it convincing
- It includes essentially every person in Denmark who started the drug for weight loss.
- Pharmacy records are objective. They don't rely on people remembering or reporting honestly.
- The authors tested 30-, 60- and 90-day definitions, and half-ish stopped under all of them.
- It's published in JAMA Network Open, a peer-reviewed journal.
What makes me cautious
- Filling a prescription isn't the same as taking the drug. Some people may have stockpiled, skipped doses or stretched supplies.
- The registries have no weight or BMI data, so we don't know how much weight people lost or regained.
- There's no information on individual income, only the average income of each person's area.
- Denmark doesn't pay for the drug. Stopping rates could be lower where insurance covers it, or higher where prices are steeper.
- The "who stops" results are associations. They don't prove that being young or male causes people to stop.
| This study shows | This study does not show |
|---|---|
| About half of Danish users stopped filling prescriptions within a year | Exactly why each person stopped |
| Young adults and men stopped more often | That age or sex causes people to stop |
| About 1 in 4 who stopped restarted within 3 months | How much weight people regained |
| Stopping was common in every group | Whether the same happens where the drug is covered by insurance |
What this means for you
If you're thinking about semaglutide for weight loss, this study is a useful reality check. Starting is the easy part.
A few things worth thinking about before you start:
- Plan for the long term. Evidence so far suggests the benefits last only as long as you take it. Ask your doctor what "long term" means for you.
- Check the cost for a full year, not a month. If you're paying yourself, budget for the whole year upfront.
- Talk about side effects early. Stomach problems are common, especially at first. A doctor may be able to adjust the dose rather than you stopping.
- Don't stop, pause or stretch doses on your own. Talk to your doctor first, so you can plan how to protect the progress you've made.
- Keep up the habits. Diet, activity and sleep still matter, on the drug and off it.
If you're already on it and struggling, you're far from alone. Half of the people in this study were in the same boat.
For a trustworthy overview of treatment options, the NHS explains how obesity is treated, including weight-loss medicines.
This CBC News report covers the BMJ review on how quickly weight returns after stopping these drugs:
What we still don't know
- Why did each person stop? Cost, side effects and disappointment all play a part, but this study can't separate them.
- What happened to their weight? The registries didn't record it.
- Would insurance coverage change things? Countries that pay for the drug could see very different stopping rates.
- Is on-and-off use harmful or helpful? With 1 in 4 restarting, we need to know what cycling does to weight and health.
- Will newer drugs and pills do better? Tirzepatide and oral versions may change the picture.
- Can lower "maintenance" doses work? If they do, the drug could become cheaper and easier to tolerate long term.
My take: the real challenge is staying on it
What I like about this study is its honesty.
It doesn't ask whether semaglutide works. We know it does.
It asks the question that matters to real people: can they stick with it?
And for about half, the answer was no, at least within the first year.
That's not a failure of willpower. It looks much more like a problem of cost, side effects and a treatment that seems to need to last for years.
If these drugs are going to change public health, making them affordable and easier to stay on matters as much as making them work.
Paper: Discontinuation of Semaglutide Therapy for Obesity Management
Published: JAMA Network Open, 2026-08-28
Study: Nationwide registry-based cohort study, December 2022 to November 2024, with up to 12 months of follow-up
Who: 157,822 adults in Denmark without diabetes who started semaglutide for weight loss
Funding: Aarhus University researchers; their department receives grants for unrelated studies, and one author reports grants from several drug companies, including semaglutide's maker Novo Nordisk, outside this work
Evidence: Strong — a complete national dataset for how many people stop, but it can't say why
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