How much weight will you lose on Ozempic, Wegovy or Mounjaro?
For people already taking a GLP-1 or holding a prescription for one. You get your projected weight trajectory, the point where it flattens out, and why that happens — worked out from the outcomes of the published trials.
This tool does not tell you whether a GLP-1 is right for you, and it prescribes neither a drug nor a dose. It answers one question, for people who have already started or are about to: what should I expect my weight to do, and when does it stop?
Your projected weight trajectory
The dose you are on now or building up to, not the one you started on. It is on your prescription.
If you do not know it, we estimate it. That estimate effectively only looks at your BMI, so it runs high for muscular people.
Pick your drug and dose, then fill in your age, height and weight. We calculate as you type: nothing is sent or stored.
Your projected weight trajectory
Part of this trajectory sits below a healthy weight
How far apart people landed
Why the weight loss stops
Roughly what you would be eating
And in a few years?
What this number is and is not
- This is the average of a trial group, worked through for your body. Differences between people are large: two people on the same dose can end up far apart.
- Do not race the drugs against each other here. The trials used different analysis methods, so the numbers are approximate rather than a head-to-head. That is why the tool shows one drug at a time.
- The evidence behind Saxenda is thinner. Its trial was analysed with an older method, which means the figure cannot be set directly alongside the others.
Where these figures come from
This tool is for people already taking a GLP-1 or holding a prescription for one. It prescribes neither medication nor dosage and is not medical advice. The figures come from published research and describe an average: differences between people are large and your own outcome may fall well outside it. Discuss your treatment with the doctor who prescribes your medication.
Outside the weight range this was studied in
This tool is for people already taking a GLP-1 or holding a prescription for one. It prescribes neither medication nor dosage and is not medical advice. The figures come from published research and describe an average: differences between people are large and your own outcome may fall well outside it. Discuss your treatment with the doctor who prescribes your medication.
We are not giving a number here
No usable trial outcome has been published for this combination of drug and dose, so we calculate nothing. Inventing a number would be easier than this, and worth nothing.
This tool is for people already taking a GLP-1 or holding a prescription for one. It prescribes neither medication nor dosage and is not medical advice. The figures come from published research and describe an average: differences between people are large and your own outcome may fall well outside it. Discuss your treatment with the doctor who prescribes your medication.
What does this tool calculate?
You pick your drug and your dose. Each pairing has a published trial outcome behind it: the average weight loss participants achieved, over that trial's duration. We translate that percentage to your body — at the same percentage, someone weighing 65 kg loses a very different number of kilos than someone weighing 140 — and then work the trajectory through a validated energy model. So you see not just the end point, but the path there and the level it flattens out at.
Why is this number different from the one in the news?
Because in trials like these you can choose who to count. Count only the people who stayed on the drug to the end and the percentages come out considerably higher — those are the figures that reach press releases. We use the outcome that counts everyone who started, including those who stopped along the way. It is lower, and it is the more honest picture of what actually happens.
Why does it flatten out?
Your energy expenditure tracks your weight. Get lighter and you burn less, and on top of that your expenditure drops a little further when you eat less for a long stretch. Your intake, meanwhile, stops moving with it. At some point the two meet and there is no deficit left. That is the plateau. It is not a sign that something is going wrong: it is why weight loss is a curve in every trial and never a straight line.
What is worth measuring while you lose weight?
Rapid weight loss leaves traces in your blood. Your blood sugar and insulin fall, your lipids shift, your liver values move with them. And because you are eating a great deal less, shortfalls in iron, vitamin B12 and vitamin D turn up more often than people expect. A baseline before you start is what makes the difference later: without a starting point you cannot tell whether a value has changed or has always been that way.
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Frequently asked questions
How much weight do you lose on Ozempic?
Ozempic is the diabetes name for semaglutide, at doses up to 2.0 mg weekly. In the trial where those doses were tested, in people with type 2 diabetes, participants lost an average of roughly 5.7 percent (1.0 mg) to 6.4 percent (2.0 mg) of their body weight over 40 weeks. The far higher numbers you meet online belong to Wegovy: the same drug, but 2.4 mg weekly and studied in people with obesity. The two cannot simply be set side by side — different dose, different trial population, different duration — but the gap is large, and it explains why expectations of Ozempic often run too high.
How much weight do you lose on Wegovy?
In STEP 1, the trial the approval rests on, participants on semaglutide 2.4 mg weekly lost an average of 14.9 percent of their body weight over 68 weeks; the placebo group lost 2.4 percent. That average hides a lot of spread: around 86 percent of participants reached at least 5 percent, and around a third reached 20 percent or more. So the average is not what you should expect — it is the middle of a wide distribution.
How much weight do you lose on Mounjaro?
In SURMOUNT-1, over 72 weeks: an average of 15.0 percent on 5 mg, 19.5 percent on 10 mg and 20.9 percent on 15 mg weekly. These are the figures that count everyone who entered the trial — not the higher ones that look only at the people who stayed on the drug, which are the ones that reach press releases.
How much weight do you lose on Saxenda?
In the SCALE trial, participants on liraglutide 3.0 mg daily lost an average of roughly 8 percent of their body weight over 56 weeks. Saxenda is the oldest of the four drugs and is injected daily rather than weekly. Its trial was also analysed with an older method, which means this figure cannot be set precisely alongside the others in any case.
Why has my weight loss stopped even though nothing changed?
Because your energy expenditure falls along with your weight. Every kilo you lose lowers what you burn in a day, and on top of that your expenditure drops a little further when you eat less for a long stretch. Your intake does not move with it. At some point the deficit you started with is no longer a deficit, and the curve flattens. This happens in every trial and with every drug; it is not a sign that the drug has stopped working.
Does the weight loss hold if I stay on the drug?
Partly. Semaglutide 2.4 mg has been followed for four years in the SELECT trial: average weight loss there sat around 10 percent after four years, against nearly 15 percent at 68 weeks. So some of it creeps back while people remain on the drug. This tool models staying on it; what happens when you stop is a question for the doctor who prescribes it.
Which blood values are worth tracking on a GLP-1?
Three groups. Safety values: pancreas (amylase and lipase), liver (ALT) and kidney function. Progress values: fasting glucose, HbA1c, fasting insulin and your lipids — these often move earlier and more clearly than the scale does. And deficiencies: ferritin, vitamin B12 and vitamin D, because eating a great deal less means taking in a great deal less. The most useful moment is a baseline before or early in your treatment, since without a starting point a later result is hard to read.
What it does to your blood does not show on the scale
Your blood sugar, insulin, liver and pancreas all shift while you lose weight, and when you eat a great deal less, iron, vitamin B12 and vitamin D drop more often than people expect. SlimmerLab measures those values, assessed by a doctor.
View the GLP-1 baseline panel