How much weight can you lose in three months on a GLP-1?
Three months on a GLP-1 typically produces between 5 and 9 per cent of starting body weight, which is roughly 5 to 9 kg for a 100 kg person. Tirzepatide sits at the top of that range and liraglutide at the bottom. The figure is lower than most people expect because the first four to eight weeks are spent on starting doses that are not intended to shift weight. A more useful way to read month three is as the point where the curve gets steep, not the point where the result is in.
What three months looks like on each treatment
The honest ranges, drawn from the registration trials and interpolated to around week twelve.
- Mounjaro (tirzepatide). Roughly 8 to 10 per cent. The steepest early curve of the four.
- Wegovy (semaglutide 2.4 mg). Roughly 6 to 7 per cent, held back by a 16-week titration.
- Ozempic (semaglutide 1 mg). Roughly 4 to 5 per cent. It is a diabetes dose, not a weight-management one.
- Saxenda (liraglutide 3 mg). Roughly 4 per cent, and it is a daily injection rather than weekly.
For a person starting at 100 kg, that is a spread of about 4 kg to 10 kg depending on which treatment they are on. It is a large difference, and it is the main reason the choice of drug matters more than most of the other decisions people agonise over.
Why month three is the wrong place to judge
Every one of these treatments is titrated, and the titration eats most of the first quarter.
On Wegovy the schedule runs 0.25, 0.5, 1.0, 1.7 and finally 2.4 mg, four weeks at each step. You reach the dose the trial was built around at week seventeen. So a three-month verdict on Wegovy is a verdict delivered before the treatment has properly started.
Mounjaro reaches a therapeutic dose faster, which is part of why its three-month figure is higher. That is a difference in schedule as much as a difference in potency.
What a good result actually looks like at twelve weeks
Clinically, the threshold most guidelines use is 5 per cent of body weight. That is the point at which measurable improvements in blood pressure, blood lipids and blood sugar tend to appear, and it is a great deal less than the figure most people set for themselves.
If you are at or above 5 per cent by week twelve, the treatment is working as intended. Below that, and on an adequate dose, it is worth a review rather than a longer wait.
One practical note: weigh fortnightly, at the same time of day, in the same clothing. Weekly weighing in the first three months mostly measures fluid, and the noise is larger than the signal you are looking for.
What makes the difference between 4 per cent and 9 per cent
Some of it is the drug. A surprising amount of it is not.
- Protein. Roughly 1.2 to 1.6 g per kilogram of body weight daily. Appetite suppression makes this genuinely hard, and it is the single most common failure.
- Resistance training. Two or three sessions a week. Without it, a substantial share of what you lose is muscle.
- Reaching an adequate dose. People who stall at a low dose because of side effects lose less, which is expected rather than surprising.
- Alcohol. Passes straight through the mechanism and is the most common invisible reason for a flat month.
- Sleep. Poorly slept people eat more and train less. It is unglamorous and it is real.
The part nobody puts in the brochure
A meaningful share of what you lose in the first three months is lean mass, not fat. Across the GLP-1 literature, estimates of lean mass as a proportion of total weight lost range from around a quarter to, at higher doses and without resistance training, well over a third.
That matters because muscle is metabolically active and losing it makes long-term maintenance harder. A three-month result of 6 per cent with protein and resistance training is a better outcome than 9 per cent without them, even though the scale disagrees.
What happens after month three
This is where the curve gets useful. Between months three and twelve is where the majority of total weight loss occurs on every one of these treatments. In SURMOUNT-1 the average at 72 weeks was 20.9 per cent, and in STEP-1 it was 14.9 per cent at 68 weeks. Neither of those was anywhere near complete at week twelve.
So the honest framing is that three months tells you whether the treatment is working, not how well it will work. Those are different questions and only the first one can be answered that early.
Weight loss in 3 months: common questions
For someone starting around 100 kg, 5 kg is 5 per cent of body weight, which is the threshold most clinical guidelines use to define a meaningful response. It is a normal and adequate result at twelve weeks, particularly on semaglutide.
Roughly 8 to 10 per cent of starting body weight, which is about 8 to 10 kg for a 100 kg person. Tirzepatide reaches a therapeutic dose faster than semaglutide, which is part of why its three-month figure is higher.
Roughly 6 to 7 per cent. Wegovy has a 16-week titration, so at three months most people have only just reached the 2.4 mg dose the trials were built around.
The commonest reasons are still being on a low dose, protein intake too low, no resistance training, or liquid calories. A minority of people are genuine low responders. Two kilograms at twelve weeks on an adequate dose is worth raising with your prescriber.
Later. The first four to eight weeks are spent on starting doses that are not intended to shift weight. The steepest part of the curve runs from roughly month three to month twelve on every one of these treatments.
Estimates across the GLP-1 literature range from about a quarter of total weight lost to over a third at higher doses without resistance training. Adequate protein and two or three resistance sessions a week substantially reduce it.