How much weight should you lose a week on Mounjaro?

What SURMOUNT-1 actually recorded, and why 'per week' is the wrong unit to fixate on

The headline figures from SURMOUNT-1 are striking: participants on the 15mg maintenance dose lost around 20–21% of their starting body weight over 72 weeks. Averaged out, that works out to roughly 0.5–1 kg per week across the whole period. But those averages mask a shape that almost nobody matches evenly. Weight loss on tirzepatide tends to come quickly in the first few months, slow during mid-treatment, and then plateau or resume as the dose increases. If you want to understand how much you lose a week on Mounjaro and why that figure shifts so much across the treatment course, the evidence behind those patterns is worth reading before fixating on a single number. Expecting a steady 1 lb every seven days, week after week, is likely to lead to unnecessary frustration.

The NICE appraisal of tirzepatide (TA1026, published December 2024) uses 5% weight loss at six months on the highest tolerated dose as a clinical checkpoint, which puts the focus firmly on medium-term progress rather than weekly numbers. That framing is deliberate. Clinicians look at a longer arc.

For a dose-specific perspective on what the evidence shows at 5mg, the 5mg Mounjaro weight-loss page covers that stage in detail.

The factors that genuinely shape how much you lose each week

Starting weight matters. Someone beginning treatment at 130 kg will typically see larger absolute losses early on than someone at 90 kg, even if the percentage reduction is similar. Starting dose matters too: 2.5mg is a tolerability step designed to settle your system before the first therapeutic increase, so the early weeks often produce modest numbers on the scale.

Diet and activity play a real role alongside the medicine. Mounjaro reduces appetite, but what you eat in the window you do feel hungry influences the outcome significantly. Protein adequacy, hydration and strength-based activity help preserve lean mass as weight falls, which in turn supports a healthier metabolic rate long-term. Our guide to eating on Mounjaro goes into the practical detail.

Individual biology is the other variable nobody controls: gut-hormone sensitivity, thyroid function, sleep quality and stress all affect the rate. Two people on the same dose, eating similarly, can lose weight at meaningfully different speeds. That is not a treatment failure on either side.

A quick check you can do right now: weigh yourself once a week, same time, same conditions (morning, before eating), and record the number. Compare monthly trends rather than day-to-day fluctuations. One minute's effort, far more useful than daily weigh-ins.

What private Mounjaro treatment costs, and what a fair price actually covers

Since Eli Lilly raised UK list prices from September 2025, the reported market range for private Mounjaro treatment sits at roughly £149–£375 per month by dose and provider. Those are widely reported figures from the period; actual prices depend on the pen strength and the service around it. The full Mounjaro pricing page covers the current picture in more detail, and you can also compare what different clinics charge per injection.

Headline prices do not always tell the whole story. Consultation fees, prescription fees, delivery charges and any ongoing clinical support are sometimes bundled in, and sometimes are not. Worth reading the small print before assuming a lower number means a better deal.

At nume, we are not the cheapest option out there, and we did not set out to be. One price covers the consultation, the prescription, the treatment, next-working-day delivery and seven-day aftercare. No subscriptions, no auto-renewals. The specifics are on our treatment page, where current pricing is shown directly.

Why weekly weight-loss pace is the wrong thing to compare across providers

For a prescription medicine supplied through a licensed UK pharmacy, the question of how much you should lose per week is clinical, not commercial. A prescriber looks at your total progress, your current dose, any side effects and your overall health picture. They do not set a weekly target and measure you against a leaderboard.

The MHRA has been clear in its public guidance that GLP-1 medicines are not assessed for quick or cosmetic weight loss. That framing matters when evaluating claims made by any provider about expected weekly results. Promises that sound more specific, more guaranteed or more dramatic than the trial evidence supports are worth treating with caution.

Counterfeit pens remain a real risk in the UK market, the MHRA has a reporting route for suspect sellers, and you can verify any online pharmacy on the GPhC register. For a prescription medicine, the right measure is not the cheapest listing; it is a genuine, clinically supervised supply from a pharmacy you can check. The clinical process at nume is described on our about us page if you want to know exactly what that looks like.

If you are weighing up what realistic progress looks like across the full treatment course rather than week by week, the overall Mounjaro weight-loss expectations page covers that, and there is a tirzepatide-specific view that puts the SURMOUNT results in a broader clinical context.