How Much Weight Will I Lose on Mounjaro?

The trial numbers are real, but they're not a guarantee for you personally

The SURMOUNT-1 trial, published in the New England Journal of Medicine, randomised 2,539 adults with obesity over 72 weeks. At the 15mg dose, average weight reduction was around 20–21% of starting body weight. That figure gets quoted often (and it is genuinely impressive) but it represents an average across thousands of participants, some of whom lost considerably more and some considerably less.

Several factors pull the result up or down. How much weight you carry to begin with matters: a higher starting BMI typically means a larger absolute loss in kilograms, even when percentages are similar. Whether you reach and stay on the highest dose matters too, the evidence at 5mg shows meaningful but smaller reductions than at 15mg. Consistency with a reduced-calorie diet and increased activity, as required by the licence, adds significantly to the outcome. And individual biology (how your body responds to dual GIP and GLP-1 receptor activation) varies in ways no trial can predict for you specifically.

NICE's appraisal of tirzepatide (TA1026) notes that continuing treatment should be reviewed if less than 5% weight loss is achieved after six months at the highest tolerated dose. That's a useful benchmark: the medicine is working for most people who stay on it, but it isn't working identically for everyone. If you're wondering how much you'll lose on Mounjaro, a prescriber can talk through what realistic progress looks like for your situation.

What UK private pricing actually includes, and what it sometimes doesn't

Understanding what you might lose on Mounjaro is one question. Understanding what it costs to lose it is another. UK private treatment is priced per pen (each pen covers four weekly doses), and the amount you pay per month rises as your dose increases. Since Eli Lilly raised Mounjaro's UK list price from 1 September 2025, typical private prices across providers have ranged roughly £149–£375 per month by dose, as widely reported following Lilly's announcement. Those figures are market context, hedged, and will shift.

The more useful question is what a quoted price actually covers. Some providers show a headline figure that excludes the consultation, the prescription fee, and delivery. Others charge monthly subscriptions that continue whether or not you need a repeat. On our Mounjaro price page you'll find more detail on how UK private pricing is structured and what to look for when comparing.

At nume, one transparent price covers the consultation, the prescription, the treatment, free next-working-day DPD delivery and 7-day aftercare support. There's no subscription and no auto-renewal. A real clinician reviews your answers the same day, your consultation lands on a prescriber's desk, not in a queue for a bot. We lose the price comparison on purpose. What that buys you is clinical oversight, a verified supply chain, and no surprises on the invoice.

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

Mounjaro is a Prescription-Only Medicine. The MHRA has warned publicly about counterfeit weight-loss pens sold online and via social media, fake pens have contained insulin, and there have been hospitalisations. In 2025, enforcement operations seized around 20 million doses of illegally traded weight-loss medicines (roughly £45m street value), and the first illicit UK site manufacturing counterfeit tirzepatide pens was raided. You can read the MHRA's guidance on spotting unsafe sellers at the Yellow Card reporting site, where suspect sellers can also be reported.

A small monthly saving isn't the measure that keeps you safe. Legitimate supply means genuine medicine from the authorised UK supply chain, dispensed by a pharmacy you can verify. Any online pharmacy can be checked against the GPhC register, and we'd encourage you to check ours (registration 9012878) before you order from anyone. Sellers offering these medicines without a prescription, or attached to discount codes from unverified sources, are a red flag worth taking seriously.

If you want to understand the full weight-loss picture (how much you might expect to lose, over what timeframe, at which dose) our tirzepatide weight-loss guide covers the trial evidence in depth. Many people also find it helpful to read about how much weight to expect in the first week on Mounjaro, since early results can shape expectations for the weeks that follow. For a fuller look at what Mounjaro is and how it works, the Mounjaro overview is a good starting point, and our weight-loss treatment page sets it alongside other licensed options. When you're ready to take the next step, you can speak to our prescribers through a free consultation, order by 12pm Monday to Friday and, once clinically approved, treatment goes out the same day.