What a Mounjaro weight loss chart tells you — and what it doesn't

What the SURMOUNT-1 results actually look like week by week

The SURMOUNT-1 trial, published in the New England Journal of Medicine, followed 2,539 adults with obesity over 72 weeks. Participants taking tirzepatide 15mg lost an average of around 20–21% of their starting body weight. The 10mg group averaged roughly 19.5%, and the 5mg group around 15%.

What no simple tirzepatide weight loss chart can fully capture is the shape of that loss. Early weeks often bring the most noticeable change, partly because the body responds to reduced calorie intake and partly because appetite suppression can be pronounced before tolerance sets in. After around 20–24 weeks, weight loss typically continues but more gradually, often levelling into a slower plateau phase before maintenance. The individual spread in that trial was wide, some participants lost considerably more than the average, others less. A chart showing a smooth downward curve to a fixed end-point is a statistical summary, not a personal forecast.

NICE reviewed this evidence in depth in Technology Appraisal TA1026 and recommended tirzepatide for adults with a BMI of 35 or above plus at least one weight-related condition, with lower thresholds applying for some ethnic backgrounds. If you're curious how those criteria map to your own situation, the Mounjaro weight loss overview lays it out clearly.

Why weight loss curves differ between people, and between doses

The doses in the licensed UK schedule (2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, 15mg) are not interchangeable rungs on a results ladder. The lower doses exist primarily to let the body adjust before stepping up, gastrointestinal side effects like nausea, reflux and loose stools are most common at the start or after an increase, and titrating slowly reduces them. The Mounjaro dosing chart explains the schedule in detail.

Weight response at lower maintenance doses is also clinically meaningful. A person who reaches their highest-tolerated dose at 10mg and stays there may achieve results closer to the 15mg average than raw trial comparisons suggest, because individual biology varies considerably. Factors including starting weight, metabolic health, diet quality, sleep, activity level and how consistently the pen is taken each week all shift the curve.

One practical point worth knowing: Mounjaro KwikPens are stored in the fridge, ideally away from the freezer compartment, many people keep theirs in the fridge door alongside everyday items, which makes the once-weekly routine easier to embed. For exact temperature windows, the Patient Information Leaflet that comes with your pen is the definitive reference.

For a broader look at how tirzepatide compares with semaglutide using the same evidence base, the tirzepatide chart page puts the two datasets side by side.

What charts can't tell you, and what clinical review adds

A chart is a population average rendered as a line. It tells you what happened across thousands of trial participants under controlled conditions; it cannot tell you what will happen to one specific person in real life. That gap matters, and it's why any legitimate use of Mounjaro involves ongoing clinical assessment rather than a fixed chart to follow.

Prescribers look at how you're responding, what side effects you're experiencing, whether your dose is being tolerated, and whether continuing is still the right call. NICE's guidance specifies that if less than 5% body weight is lost after six months at the highest tolerated dose, continuing should be reviewed. That clinical check-in is a feature, not a formality.

If you want a sense of what the cost of private treatment looks like before starting, the Mounjaro price comparison page gives honest market context. And if you'd like to understand how the Mounjaro injection fits into a broader treatment plan, our prescribers review each consultation individually, assessing your health history, current medications and goals before anything is approved. A question our prescribers hear most weeks is whether a weight loss chart is a reliable guide; the honest answer is that it's a useful starting reference, not a personal roadmap.

For a full picture of what tirzepatide is, how it's used and who it's licensed for, this overview covers the mechanism, the evidence and the access routes clearly. You can also learn more about tirzepatide as the medicine behind the brand name.

If you're ready to find out whether treatment is right for you, start your free consultation and a named clinician will review your answers the same day.