Mounjaro After 1 Year: Trial Results vs Real-World Data

After Mounjaro 1 year in, you will read −20.9%, −15.3% or −8.7% depending on which source you consult. All three figures are accurate. What separates them is neither the drug nor the dose: it is who gets counted. The first comes from a clinical trial where participants are titrated per protocol and closely monitored. The second comes from real-world data, measured in patients still on treatment after a year. The third splits those who continued from those who stopped. This article tells you which one applies to you, why they diverge so widely, and why the single biggest determinant of the one-year result is not the one that gets the headlines.

How much weight do you lose on Mounjaro 1 year in?

In the real world, among patients still on treatment after a year, average loss is 15.3% of starting body weight. In the SURMOUNT-1 trial it reached 20.9%. The gap comes from the population being measured, not from any difference in how well the drug works.

Here are the three readings side by side, with what each one actually measures.

That last row needs two clarifications, because it is very often misquoted. The 8.7% figure applies to patients who did not stop treatment, not to everyone who started. And the Gasoyan cohort combines semaglutide and tirzepatide: it is not a “Mounjaro” number. It also comes from a single health system, which helps explain why it sits below the real-world study published in JAMA Internal Medicine.

If you are mid-treatment and want a closer marker, we have published the six-month checkpoint, which describes the intermediate trajectory.

What a year on Mounjaro means in pounds

Based on the 15.3% real-world figure, here is what a year on Mounjaro works out to by starting weight. These are population averages, not guaranteed individual results.

To place your own starting point, you can check your BMI and weight-loss projection.

Mounjaro: why the trial gives a higher number than real-world data

Three structural differences explain the gap of more than 5 points between the trial and everyday practice, and none of them involves the molecule. Titration is carried out per protocol up to the high doses, whereas in practice it often stops lower. Medical follow-up is close, with scheduled appointments that real life does not always provide. And participants are selected against inclusion criteria that exclude a share of the situations seen in clinic.

The 20.9% figure comes from SURMOUNT-1, published in the New England Journal of Medicine, at the 15 mg dose over 72 weeks and on the treatment-regimen estimand. We are not rehearsing trial protocols here: that detail belongs to a dedicated article.

What stopping Mounjaro partway through the year changes

This is the most decisive factor and the least discussed. In Gasoyan, one-year loss falls from 8.7% among those who continue to 6.8% with late discontinuation, and to 3.6% with early discontinuation. The gap between staying on treatment and stopping early is therefore wider than the gap measured between two competing molecules.

Put differently, the useful question after Mounjaro 1 year in is not only “how much do you lose?” but “what makes someone still be there after a year?”. An article that only discussed efficacy would miss the dominant factor.

A point about method and tone that matters at least as much as the number. The documented reasons for stopping are overwhelmingly structural: gastrointestinal intolerance, cost of treatment, supply shortages, difficulty accessing a prescriber or a refill. These are not failures of willpower. Framing discontinuation as a motivation problem is both wrong on the evidence and counterproductive: it discourages exactly the people who would benefit from raising it with their doctor. These results come from Gasoyan’s work published in Obesity, in a cohort of 7,881 patients combining semaglutide and tirzepatide.

What weighs on the result after 1 year on Mounjaro

Three factors stand out in the available data. They are not ranked by importance: the studies do not allow that.

Continuity of treatment. This is what Gasoyan quantifies, and the gap is more than twofold between continuing and stopping early. It is also the factor an appointment can act on most, since most reasons for stopping — tolerability, cost, supply — are worked through with a clinician rather than alone.

The dose reached during the year. This explains much of the trial-to-real-world gap: trial protocols carry titration up to the high doses, which is not the case for every real-world path. Knowing where your own titration stands helps interpret your curve, and is a question for the appointment rather than a decision to take alone.

Baseline HbA1c, for patients with diabetes. In people living with type 2 diabetes, starting glycaemic control affects the weight loss achieved. Someone with diabetes comparing themselves to figures published for non-diabetic populations is comparing themselves to a population that is not their own.

And after the first year on Mounjaro?

Weight loss continues beyond the first year, at a markedly slower pace than in the early months. Two questions then arise that this article deliberately does not address: how long to stay on treatment, and what happens to weight if treatment stops. Both are subjects in their own right, with their own data, covered in dedicated articles. Either way they are decided with your doctor, based on your result and your situation.

Frequently asked questions

How much weight do you lose on Mounjaro in 1 year?

Roughly 27 to 37 lb (12 to 17 kg) depending on starting weight, based on the 15.3% observed in real-world data among patients still on treatment after a year (Rodriguez et al., JAMA Internal Medicine, 2024, in 18,386 matched patients). Starting from 198 lb, that is about 30 lb. It is a population average, not a guaranteed individual result.

Why do Mounjaro numbers vary so much between sources?

Because they do not count the same people. The clinical trial measures participants titrated per protocol with close follow-up, giving 20.9%. Real-world data measure patients still on treatment at one year, giving 15.3%. Gasoyan’s work splits patients by whether they continued or stopped. None of these figures is wrong; they answer different questions.

What happens if you stop Mounjaro before a year?

In Gasoyan, one-year loss is 8.7% among those who continue, 6.8% with late discontinuation and 3.6% with early discontinuation, in a cohort combining semaglutide and tirzepatide. The reasons for stopping are overwhelmingly structural: tolerability, cost, supply, prescriber access. If you are considering stopping, that is a conversation for your doctor, who often has options.

Do you keep losing weight after the first year?

Yes, but at a markedly slower pace than in the early months. Questions about treatment duration and weight maintenance after stopping rest on different data from those presented here and are decided with your doctor.

Do you need to reach the maximum dose to get these results?

The 20.9% figure from SURMOUNT-1 corresponds to the 15 mg dose. The 15.3% real-world figure covers patients across a range of doses, which explains part of the gap. Dose reached matters, but it is not the only factor, and the dose level appropriate to your situation is a matter for your prescriber.

Medical disclaimer. This article is strictly informational and does not replace medical advice. The figures cited are population averages drawn from published studies and do not predict your individual result. Nothing here constitutes a dose recommendation or a course of action: any decision to start, continue or stop a treatment should be made with a healthcare professional. Information current as of 1 August 2026.

To track the effect on your own curve, logged data beats vague recollections on the day of your appointment: the MounjaGO app brings together weight, doses, side effects and meals, and turns them into a PDF report for your doctor — $12 for lifetime access, no subscription.