How Much Can You Lose on Mounjaro — and What Shapes the Result?

What does the trial data actually show about weight loss on Mounjaro?

The headline figure from SURMOUNT-1, the pivotal trial published in the New England Journal of Medicine, is around 20–21% average body-weight reduction at the 15mg maintenance dose over 72 weeks. That trial ran with 2,539 adults with obesity and no type 2 diabetes, a large, well-powered study, not a small pilot.

At lower maintenance doses the averages were lower: roughly 15% at 5mg and around 19.5% at 10mg. Those figures matter because not everyone reaches 15mg; titration is gradual and some people settle at a lower dose that suits them better. How much you lose on the 5mg dose, for instance, is a different question from the headline number, and our 5mg results page explores that specifically.

In a head-to-head comparison, SURMOUNT-5 found tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks, a finding the NICE appraisal of tirzepatide also referenced when recommending it. These are population averages, though. Some people lose more, some less. If you are just starting out and want to understand how much weight you can lose on the 2.5mg starting dose, that opening phase looks quite different from the longer-term picture. Results over the first three months look different from 72-week outcomes, and if you are curious about the early trajectory, the three-month results breakdown addresses that directly. The honest answer is: the range is wide, and a prescriber is the right person to set realistic expectations for your situation.

How does Mounjaro's private cost affect how much value you actually get?

UK private pricing for weight-management treatment is set per pen or per monthly supply and varies between providers. Following Eli Lilly's UK list-price increase in September 2025, typical private prices across the market have ranged roughly £149–£375 per month depending on dose and provider, as widely reported at the time of the change. Those are market-range figures, not a price guarantee from any single service.

What that headline number often excludes is worth checking in under a minute: look at any provider's checkout and count whether the consultation fee, prescription charge, delivery cost, and ongoing clinical support are included or itemised separately. On some platforms they are not. That gap can make a lower-quoted price considerably less low by the time you have paid for the prescription and the first delivery.

For more on how the market is structured and what to look for when comparing, our Mounjaro cost breakdown sets it out clearly. And if you are weighing up paying in instalments, we also offer Klarna, details on the Mounjaro pay-with-Klarna page.

At nume, one price covers the consultation, the prescription, the treatment, and free next-working-day tracked delivery. We are not the cheapest option in the market, and that is a deliberate choice. The difference goes into clinical infrastructure: identity verification, live weight checks on video, GP notification, and a named prescriber reviewing every single order.

Why is 'cheapest' the wrong question for a prescription medicine?

Mounjaro is a Prescription-Only Medicine. The MHRA has warned publicly and repeatedly about counterfeit weight-loss pens sold online, including a 2025 enforcement operation that seized around 20 million doses of illegally traded GLP-1 medicines with a street value of roughly £45 million, and the first illicit UK site producing fake tirzepatide pens was raided in Northampton that same year. Some counterfeit pens seized earlier in the campaign were found to contain insulin rather than the labelled medicine.

Any seller offering these medicines without requiring a prescription and a clinical assessment is operating outside UK law. Prices far below the market range are a red flag, not a bargain. If you ever want to verify a pharmacy, the GPhC register entry for our pharmacy takes seconds to check, every legitimate online pharmacy should appear there. Suspect sellers can be reported directly to the MHRA via the Yellow Card scheme.

The metric that matters for a POM is whether you are getting genuine medicine, assessed by a real clinician, through a pharmacy you can verify. Price answers a different question entirely. For an overview of how Mounjaro treatment works at nume, sorry, at our Mounjaro service page, all of that is laid out plainly. If you are still deciding whether treatment is right for you, our weight-loss treatment overview compares the options available.

Ready to find out what is realistic for you?

How much you can lose on Mounjaro is ultimately a clinical question as much as a statistical one. The trial averages give a benchmark; your prescriber gives a personalised assessment. If you want a clearer sense of what typical progress looks like week by week, our page on how much you lose a week on Mounjaro breaks that down in detail. Our clinical team (you can read about their approach on the clinical team profile) reviews every consultation the same day. There are no automated decisions here. If you have questions before you start, our FAQs cover the most common ones, and our team is reachable via the contact page seven days a week.

When you are ready, speak to our prescribers through a free consultation. It is the only legal starting point for treatment, and it costs nothing to find out where you stand.