How Much Can I Expect to Lose on Mounjaro? (October 2026)

01 · The core answer

What you can realistically expect to lose on Mounjaro

The most reliable answer comes from the SURMOUNT-1 trial: 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. Individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

The spread around those averages matters as much as the averages themselves. At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight.² Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.² So most people in the trial lost a meaningful amount, but the exact result sat on a wide range. You can read more on what people typically lose and on average weight loss figures.

02 · Reading the figures

How to read these numbers for your own situation

Treat the trial figures as a map of the terrain, not a forecast for your own result. The trial measured outcomes at 72 weeks, which is well over a year. Nobody should expect to reach those averages in a few weeks, and a short-term snapshot will always look smaller than the headline figure.

Three questions help you place yourself. First, which dose are you likely to settle on? Higher maintenance doses were associated with larger average losses in the trial, but the right dose is the one you tolerate and respond to, agreed with your prescriber. Second, how long can you stay on treatment? The trial averages reflect sustained treatment, not a short course. Third, are you changing how you eat and move? The medicine is licensed for use alongside a reduced-calorie diet and increased physical activity.¹

03 · Next step

What to do next

If you are still deciding whether Mounjaro suits you, the useful next step is a consultation, not a target number. Our free online consultation is reviewed by a GPhC-registered prescriber, who can discuss whether treatment is appropriate and which starting plan fits you. The Mounjaro pen starts at £169.99 for the 2.5mg strength, and you can see all strengths, current prices and availability on the Mounjaro pen product page. Our wider weight loss clinic page explains the full service.

04 · Trial averages explained

What the SURMOUNT-1 averages actually tell you

Mounjaro is the brand name for tirzepatide, a weekly injectable prescription medicine made by Eli Lilly. In the UK it is licensed for weight management in adults and for type 2 diabetes.¹ The best-known evidence for weight management is the SURMOUNT-1 trial.

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.²

Notice what the comparison group shows. People who made lifestyle changes alone did lose some weight, but far less than those who also took the medicine. That gap is the part of the result that the medicine contributes, and it is the fairest way to think about what Mounjaro adds on top of your own effort.

An average is the middle of a spread. Some people in any trial lose more than the average and some lose less, and the average hides both groups. That is why the trial also reports how many people crossed particular thresholds. At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight.² Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.²

Two cautions help you avoid misreading the numbers. First, the trial describes people who stayed on treatment and followed the programme alongside it, so the results do not describe someone who takes a few doses and stops. Second, a trial average does not predict your own result. Your starting weight, your dose, your eating pattern and how your body responds all shape what you see on the scales.

Percentages are also easier to apply than a single kilogram figure. A percentage scales with where you begin, so the same percentage means a larger number of kilograms for someone who starts heavier and a smaller number for someone who starts lighter. Work out your own starting weight, then apply the percentage that matches the dose you expect to reach, and treat the answer as a broad guide rather than a target.

For a deeper look at how the figures break down, our guide to how much weight you could lose sets out the same evidence from another angle.

05 · The pace of results

How quickly the weight comes off

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.¹ Trials measured results at 72 weeks, so think in months, not days, and judge progress by trend, not individual weigh-ins.

This pacing follows from how the medicine is started. Treatment begins at the lowest strength so your body can adjust, and the dose is increased in steps rather than all at once. Because larger average losses in the trial were seen at higher doses, it makes sense that the early weeks look quieter than the later months. The starter pen is not meant to deliver the headline numbers; it is meant to get you ready for the doses that might.

The dose steps up after at least 4 weeks on each dose, depending on how you respond, and the licensed ladder runs through 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg. Your prescriber decides when a step up is appropriate, based on how you are tolerating the current dose and how you are responding. Many people do not need the top of the ladder, and the right maintenance dose is individual.

Our weight loss week by week guide explains why weekly numbers bounce around.

The point worth holding on to is that slow early progress is not a warning sign. Three months in, most people are still on the lower rungs of the dose ladder, so trial-average losses at this stage are modest compared with the headline figures: in SURMOUNT-1, average weight loss built month by month, with the full 15–21% averages measured at 72 weeks, not 12.² A sensible expectation at that stage, on a standard titration, is mid single digits as a percentage of body weight, with wide individual variation.

Slower early progress does not predict failure, because the dose you respond to may still be ahead of you. If you compare yourself with someone who is further along the ladder, or with a trial figure measured over more than a year, you will almost always feel behind. Compare yourself with your own starting point and your own trend instead.

06 · The first weeks

What is normal in the first weeks

The 2.5mg starting weeks are about adjustment, and experiences differ widely. Some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal.¹

Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.¹ This is why a big drop in the first days can look encouraging and then be followed by a flat patch. Neither tells you much about the longer course. Weigh yourself under the same conditions, record the numbers, and look at the direction over several weeks rather than reacting to each reading.

Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹³ If side effects are troubling, or if you notice a new symptom that worries you, speak to your prescriber. You can also report suspected side effects through the Yellow Card scheme.¹⁹

What changes first is often appetite rather than the scales. Many people notice they feel full sooner and less hungry between meals, which is the practical effect of the medicine's action on appetite and stomach emptying.¹ That change in hunger is the tool that helps a reduced-calorie diet feel manageable. If you feel it early, it is a good sign the medicine is working as intended, even before the scale moves.

If you feel little at first, do not assume the medicine is not for you. The starter strength is there to let your body adjust, and a quiet start is common.

Many people also find it helpful to note their injection day and any symptoms in a diary or app. Our free companion app, GLPTrackr, is available for iOS and Android and is designed for tracking a GLP-1 journey. A running record makes the monthly review conversation with your prescriber more useful, because you can describe trends rather than trying to remember how each week felt.

Finally, resist the urge to chase speed. A faster start is not a better start if it comes with side effects you cannot sustain. The licensed approach of gradual steps exists so that you can stay on treatment comfortably long enough to see the benefit.

07 · Why results differ

Why two people on the same dose lose different amounts

Results differ because the trial figures are averages, and averages describe a spread of individual outcomes. In SURMOUNT-1 some participants lost much more than the average and others lost less, even on the same dose.² Several practical factors help explain why your own number may sit above or below the middle.

The dose you reach. The trial averages rose with dose, from 5mg through 10mg to 15mg.² Someone who settles on a lower maintenance dose should expect a different result from someone who settles on a higher one, and neither is doing anything wrong. The right dose is the one you tolerate and respond to.

How long you have been on treatment. The trial measured results at 72 weeks. Someone a few months in is at a different point on the same curve, so comparing your result with a long-term average will mislead you.

Food and activity. The medicine is used alongside a reduced-calorie diet and increased physical activity.¹ Reduced appetite makes eating less easier, but portions can drift back up over time, and the choices you make still shape the outcome. The lifestyle-only group in the trial lost some weight on its own, which shows these habits count.

Consistency. Treatment is weekly, so staying on schedule and attending your reviews matters. Gaps in treatment and uneven dosing make the trend harder to read.

Tolerability. Side effects can limit how quickly the dose rises. A person who needs more time on a lower dose will usually progress more slowly than someone who steps up comfortably, and your prescriber will balance the pace against how you feel.

None of this means you can control the outcome precisely. It means that the number on the scales is the product of several things working together, and only some are in your hands. The healthiest stance is to focus on what you can influence, which is consistency, food quality, activity and honest communication with your prescriber, and to let the result follow.

It also helps to remember that comparison with strangers online is a poor guide. Their starting weight, dose, timeline and habits are unknown to you, and the people who share dramatic results are not a representative sample. Your prescriber, who knows your circumstances, is a far better reference point.

08 · Plateaus

What to do when the scales stop moving

Weight loss on Mounjaro is not linear. Plateaus of a few weeks are normal and expected as the body adapts to a lower weight.¹ A flat patch does not mean the medicine has stopped working, and it is not by itself a reason to panic or change course.

Within the licence, there is a sensible sequence of responses. Start by reviewing food intake honestly, because portions drift back up without anyone noticing. Protect protein and activity, since they support a healthy approach to losing weight. Check the basics, including sleep and alcohol, which can quietly undermine progress. Then discuss with your prescriber whether a dose step-up is appropriate if you are not yet at maximum.¹

Just as important is what not to do. A plateau is not a reason to double doses or add unlicensed products. If you are tempted by products promising dramatic weight-loss claims, speak to your prescriber first.

Trends over weeks and months are far more informative than a single flat fortnight, so keep recording and look at the longer line.

Plateaus are also a good moment for a monthly review. Our aftercare includes ongoing monthly reviews, dose-titration and follow-up assessments by the prescribing team, so you have someone to talk the situation through with rather than guessing. Bring your weight record, a description of your eating pattern and any side effects, and your prescriber can judge whether a step-up, staying at your current dose or another adjustment is right.

If the plateau coincides with a stressful period, illness or a change in routine, say so. Context helps your prescriber interpret what they see. And if you are already at the top licensed dose, the conversation shifts to sustaining the progress you have made and reviewing the overall plan, rather than looking for something extra to add.

Many people find the mental side of a plateau harder than the physical side. Reminding yourself that the trial averages were reached through months of gradual change, with ups and downs along the way, can make a flat fortnight feel less threatening.

09 · Beyond the scales

Results that do not show up on the scales

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, but they are why prescribers talk about weight management as health management rather than appearance.

This changes how you might measure success. If the scale is the only number you watch, a slow month can feel like a failure even when other measures are moving in the right direction. Consider tracking more than weight: how your clothes fit, how you feel in daily activity, how your appetite behaves and any measurements your prescriber or GP arranges.

It also helps to understand why these changes tend to travel together. The medicine acts on two natural gut-hormone receptors, GIP and GLP-1, which together help regulate appetite, slow how quickly the stomach empties and improve the way the body responds to insulin.¹ In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.

Be careful with a related temptation, which is to expect cosmetic outcomes on a timetable. How your face, body shape or energy levels change depends on many things, so speak to your prescriber about what to expect. If you want to understand body-fat questions more broadly, our belly fat guide is a sensible, honest starting point.

The practical message is that a result worth having is wider than a number. Many people who begin treatment for weight reasons find that the health measures their prescriber or GP checks tell an encouraging story before, or alongside, the scales. Those outcomes deserve as much attention as the weight itself, and they are the reason ongoing review, rather than a one-off prescription, is part of responsible treatment.

Equally, none of this should be read as a promise. The measured improvements are averages from trial participants, and your own pattern may differ. Use them as context for why treatment is taken seriously, not as a checklist you must tick.

10 · Serious side effects

Serious side effects: when to get help straight away

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. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹

11 · Review, stopping and access

Reviews, stopping treatment and how to get access

Your response is reviewed by your prescriber, and that review is part of what makes realistic expectations possible. 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.¹ That is a conversation, not an automatic cut-off, and it exists so treatment continues only while it is helping you.

If you do stop, you should know how the medicine leaves your body. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears.¹ Mounjaro manages weight; it does not cure the biology behind it. In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average. Talk to your prescriber before stopping so you can plan your eating and activity for the period afterwards.

On access, Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

You complete a free online consultation, which is a short health questionnaire with no charge and no obligation. A GPhC-registered prescriber reviews it, and if they decide the treatment is not suitable, the order is refunded automatically in full. Approved orders are dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm, and delivered by free next-day tracked delivery in temperature-controlled packaging. Saturday delivery is £14.99.

Mounjaro is supplied through official LillyDirect supply, meaning genuine KwikPens direct from Eli Lilly's UK distribution. New customers save £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). Repeat orders re-check suitability, and there is no auto-shipping. Ongoing monthly reviews are included, so the realistic-expectations conversation continues as you progress.

Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary, and this page is information, not a substitute for medical advice.