How Many Calories to Lose Weight on Mounjaro (October 2026)

01 · The short answer

What calorie target should you aim for on Mounjaro?

Your target should be a modest, sustainable deficit below your own maintenance intake, agreed with your prescriber or a dietitian. Online charts that give one total for every woman and another for every man ignore your height, current weight, age, job and how much you move. Two people of the same sex can need very different amounts of food.

Mounjaro (tirzepatide) activates GIP and GLP-1 receptors. Together these help regulate appetite and slow how quickly the stomach empties, so most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.¹

A practical way to find your own number is in three steps:

• Estimate what you eat now by logging your food honestly for a typical stretch of days, before or in the early weeks of treatment.
• Use a reputable calorie calculator, or ask a dietitian, to estimate your maintenance intake from your height, weight, age and activity.
• Aim for a modest gap below that, then adjust with your prescriber based on how you feel and how your weight trends over months.

If you want the longer version, our complete UK calorie guide goes into meal structure, and our page on daily calories on Mounjaro covers the day-to-day picture.

02 · Honest answer

Why there is no fixed calorie figure

Many pages, and some AI summaries, quote exact totals for women and men and exact floors beneath them. A single calorie number is not set for people taking Mounjaro. The licence and trial evidence describe tirzepatide as working alongside a reduced-calorie diet and increased physical activity, not a particular daily total.²

A number pulled from a chart can mislead you in either direction. Set too high, you stall and wonder if the medicine is failing. Set too low, you feel tired, struggle to eat enough protein and are more likely to give up. Your prescriber sees your history and can say what is reasonable for you.

If you are already a customer or are considering treatment, the sensible next step is a conversation, not a calculation. You can see how the process works on our weight loss clinic page, and the Mounjaro pen page shows current doses and prices.

03 · Appetite versus intake

Appetite drops, but your target still matters

On Mounjaro you will probably feel full sooner, and cravings often quieten. This is the intended effect of the medicine.¹ The risk is that a small appetite leads you to skip meals or live on snacks, which makes it hard to get enough protein and other nutrients.

Treat food as something to plan rather than something you wait to feel hungry for. Small, regular, protein-led meals tend to suit people with a reduced appetite. Many people find they cannot finish portions they used to eat, so smaller plates and slower eating help.

Remember that the trial results people quote came from people combining tirzepatide with diet and exercise. In SURMOUNT-1, 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. Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.

04 · Avoiding very low intakes

Why very low calorie totals are the wrong goal

The honest answer is that the lowest possible number is not the target, and chasing it can work against you.

Mounjaro already narrows how much you want to eat. Stacking an aggressive restriction on top can leave you tired or short of protein, and this is easy to confuse with side effects of the medicine. The commonest early effects of the injection are mild nausea, altered appetite and tiredness in the first days after each injection, and they usually settle.¹³ If you are also under-eating, it becomes hard to tell the cause.

If you are regularly dizzy, exhausted, unable to eat protein or skipping meals because you feel no hunger, tell your prescriber. That is a prompt to eat more or adjust the plan, not to push through.

People on certain other medicines, such as insulin or sulfonylureas, should be especially careful because doses may need adjusting if intake falls, with a risk of low blood sugar. Mounjaro is not suitable for everyone: you should not take it if you are allergic to tirzepatide or any of its ingredients, and it should not be used during pregnancy or while trying to conceive. Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly. 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. Speak to your prescriber before changing how you eat.¹

05 · Protein, activity and basics

Protein, activity, sleep and alcohol

Calories are only part of the picture. When progress slows, the recommended responses within the licence are to review food intake honestly because portions drift back up, protect protein and activity, check the basics such as sleep and alcohol, and discuss with your prescriber whether a dose step-up is appropriate if you are not yet at maximum.²

Practical ways to apply that:

• Build each meal around a protein source such as eggs, fish, poultry, pulses, tofu or dairy, then add vegetables and a modest portion of starchy carbohydrate.
• Keep moving. Walking daily, and some resistance work if your health allows, supports the plan alongside the medicine.
• Look at liquid calories. Sweetened drinks, alcohol and large coffees add up quickly and do not make you feel full.
• Protect your sleep, since poor sleep makes food choices harder.

Our page on calories while on Mounjaro looks at everyday eating.

06 · Pace and plateaus

How fast to expect results, and what a plateau means

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. Trials measured results at 72 weeks — think in months, not days, and judge progress by trend, not individual weigh-ins.²

Early loss includes water weight, so the trend over weeks matters more than any single weigh-in.¹³

Weight loss is also not linear. Plateaus of a few weeks are normal and expected as the body adapts to a lower weight. A plateau is not a reason to double doses or add unlicensed products.² Three months in, most people are still on the lower rungs of the dose ladder, so a sensible expectation 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.²

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

07 · Signs it is working

Signs your body is changing, beyond the scales

There is no single reliable sign that you are burning fat, and we would not trust anyone who claims one. A better approach is to look at several measures together over months.

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.

Useful things to track:

• Your weight trend across weeks, not daily weigh-ins.
• Your waist measurement, taken in the same way each time.
• How clothes fit, your energy, and how easily you move.
• Any blood pressure or blood-sugar readings your clinician takes.

Our free companion app, GLPTrackr, can help you record your journey on iOS and Android, so you can show the trend at your monthly review.

08 · Mounjaro and other options

How this compares with other weight-loss approaches

Other products work differently from Mounjaro, and their effect on calories is not the same. Orlistat, for example, acts on fat absorption rather than appetite. We explain its approach in our guides on calories on orlistat and how many calories orlistat blocks.

If you are weighing up options, our overview of the Mounjaro weight loss injection explains what treatment involves. 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 primary-care rollout began in June 2025 with the highest-need groups first.⁴ Many people who meet the licensed criteria choose regulated private treatment rather than waiting.

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. This page is information, not a substitute for medical advice.

09 · Questions for your prescriber

What to ask at your review

Your monthly review is a good place to settle your own calorie question. Bring a few days of food notes and your weight trend. Useful questions include:

• Given my size and activity, what intake is reasonable for me?
• Am I getting enough protein, given my smaller appetite?
• Are my symptoms, such as tiredness or nausea, linked to the medicine or to eating too little?
• Is my progress in line with what you would expect at my current dose?
• Would a change of dose make sense, or should I wait?

Our related guides on how many calories a day to have and how many calories to consume cover the same topic from different angles.