How Many Kilos a Week Can You Lose on Mounjaro? (October 2026)

01 · The core answer

Is there a set number of kilos you lose each week?

No, there is not.

What the evidence does say is clear. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages, and individual results vary.

That loss accumulated over well over a year, with the dose stepping up along the way. Your own weekly numbers will bounce around that average, sometimes down, sometimes flat, sometimes up a little.

02 · Pace over time

What does the pace look like over time?

Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase and losses are usually modest; most measurable progress builds from 5mg onward, month by month.²

For the three-month point specifically: a sensible 3-month expectation on a standard titration is mid single digits as a percentage of body weight, with wide individual variation.² Slower early progress does not predict failure, because the dose you respond to may still be ahead of you.

03 · What to do next

What should you do with this information?

Set expectations in months, track the trend, and let your prescriber review your response. Trials measured results at 72 weeks, so think in months, not days, and judge progress by trend, not individual weigh-ins.²

If you are weighing up whether treatment suits you, our weight loss clinic explains how a consultation works. The Mounjaro pen starts at £169.99 for the 2.5mg pen at standard price; a new customer's first 2.5mg pen is £129.99 with code FIRST40. Our free consultation is reviewed by a GPhC-registered prescriber.

Related guides: How many stone can you lose on mounjaro and How many kg can i lose on mounjaro.

04 · Early weeks

What is normal in the first weeks?

Experiences differ widely in the first weeks. Some people notice appetite change and early loss in week one, while others feel little until a higher dose, and both are normal. Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.

Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle. If a symptom worries you, tell your prescriber, who can review your dose. Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing.

This is also why a big drop on the scales in the first days should not be read as your permanent weekly rate. Water shifts come first, and the steadier fat-loss trend follows over the coming months. For wider context, see our guide to what you can expect to lose across the whole course.

05 · Plateaus

Why does loss stall for some weeks?

Weight loss on Mounjaro is not linear. Plateaus of a few weeks are normal and expected as the body adapts to a lower weight.

Within the licence, the responses are practical:

• Review food intake honestly, because portions drift back up.
• Protect protein and activity.
• Check the basics, such as sleep and alcohol.
• Discuss with your prescriber whether a dose step-up is appropriate if you are not yet at maximum.

A plateau is not a reason to double doses or add unlicensed products. If you want to understand how food intake fits in, our page on calories while on Mounjaro covers it.

06 · Fast or slow

When is progress too slow or too fast?

Your prescriber reviews how you are responding. Treatment response is reviewed by your prescriber: if you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.⁴

That check is about the whole course, not a weekly target.

Loss that feels unusually rapid is worth raising with your prescriber rather than celebrating. If you cannot keep fluids down, contact your clinical team — dehydration needs medical help straight away. Gradual is the intended pattern of this treatment.

07 · Beyond the scales

Does the scale tell the whole story?

No, it does not. In trials, weight loss on tirzepatide came with average improvements in waist size, blood pressure, cholesterol and blood-sugar measures, and most participants with prediabetes returned to normal blood-sugar levels.² These are trial-average secondary outcomes, not promises.

They are why prescribers talk about weight management as health management rather than appearance. A week where the scale does not move can still sit inside a month where clothes fit differently and your waist measurement falls.

Keeping a record helps. Waist measurements, how clothes fit and how you feel are all useful alongside weight. Our free companion app, GLPTrackr, lets you log your journey on iOS or Android and see the trend rather than the noise.

08 · How Mounjaro works

Why is the effect gradual?

Tirzepatide activates two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin. In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹

Because the medicine supports a reduced-calorie diet rather than replacing it, your results depend on how that diet and your activity go as well as on the dose. Mounjaro is a once-weekly injectable made by Eli Lilly, licensed in the UK for weight management in adults. It is used alongside a reduced-calorie diet and increased physical activity, and individual results vary.

You can also see our guide to total kilos lost.