How Many Calories Should I Be Eating on Mounjaro? (October 2026)

01 · The core answer

How many calories should you eat on Mounjaro?

You should eat enough to lose weight steadily without feeling unwell, weak or unable to get nutrients in. That is a sustainable deficit, not a fixed figure. Mounjaro treatment is licensed alongside a reduced-calorie diet, so the aim is a deficit you can hold, not a perfect food list¹³.

Tirzepatide activates two gut-hormone receptors, GIP and GLP-1. These help regulate appetite and slow how quickly the stomach empties, so most people feel fuller sooner and less hungry between meals¹. The medicine lowers the effort of eating less. It does not tell you the right amount to eat.

Online calculators and general guidance give typical ranges for women and men. Treat them as a starting estimate only. Your own figure depends on height, current weight, age, sex, job and how much you move. Your prescriber or a registered dietitian can help you set a realistic target at your monthly review.

02 · What to do

A practical way to set your intake

If you are already a customer or considering treatment, our weight loss clinic explains the programme. The Mounjaro pen starts at £169.99 per month for the 2.5mg strength, and new customers save £40 on their first order with code FIRST40. A free consultation is reviewed by a GPhC-registered prescriber.

03 · Very low intakes

Eating 600, 800 or 1000 calories on Mounjaro

Eating at the very low end is not a recommended target, even if your appetite makes it feel easy. Medicine-assisted low appetite can make a person eat far less than their body needs. Very little food makes it hard to include protein at every meal, and eating much less can leave nutritional gaps¹³.

Eating much less can leave nutritional gaps, and a very low intake can make you feel tired or dizzy; if you faint, get medical help straight away. Tell your prescriber if you are eating very little rather than keeping going.

Our guide to how many calories to eat on Mounjaro goes into the numbers and the reasoning in more depth.

04 · Protein and muscle

Protein and protecting muscle

Protein matters more on Mounjaro because appetite is lower and calories are tighter. Some of any rapid weight loss comes from lean tissue, and protecting muscle protects your metabolism, strength and appearance. The two levers are adequate protein, with a protein source at every meal, which is harder when appetite is low, and resistance exercise two or more times a week. This matters more, not less, as the dose rises and appetite falls¹³.

In practice, start the meal with the protein, then add vegetables and fibre. If you only manage a few mouthfuls, make them count.

05 · What to eat

What should you eat while taking Mounjaro?

No food is banned on Mounjaro, including bananas, but some choices make treatment easier and more effective. Prioritise protein at each meal, vegetables and fibre, and regular fluids¹³.

Many people feel worse after very fatty, fried or very sugary food. Large portions sit heavily because the stomach empties more slowly, so smaller, slower meals work better. Stop when you feel comfortably full, not stuffed.

• Lean meat, fish, eggs, tofu, beans, lentils and Greek-style yoghurt for protein.
• Vegetables, salad and wholegrains for fibre and volume.
• Water, and tea or coffee without high-calorie additions.
• Treats in small portions, since nothing is forbidden.

For a fuller breakdown, see how many calories to consume on Mounjaro.

06 · Fluids, alcohol and coffee

Fluids, alcohol and coffee

Drinking enough matters more on Mounjaro than usual. Reduced appetite means less fluid from food, and vomiting or diarrhoea can dehydrate you quickly, which is the main route to the rare kidney problems reported with this class. Keep water within reach through the day¹³.

Coffee and tea are fine, as there is no interaction between Mounjaro and caffeine. Strong coffee on an empty, slower-emptying stomach can aggravate nausea or reflux for some people, and high-calorie coffee drinks are an easy place for the calorie deficit to leak. Coffee rules circulating on social media have no clinical basis.

There is no direct interaction between Mounjaro and alcohol, but drinking on a reduced appetite and emptier stomach can hit harder than usual, and alcohol adds calories that work against your goals. If you also take insulin or a sulfonylurea, alcohol increases the risk of low blood sugar. Moderation is the sensible rule.

07 · Exercise and vitamins

Exercise and vitamins

Increased physical activity is part of the licence, not an optional extra. Nothing special is required: the evidence-backed pattern is regular moderate activity such as brisk walking, plus resistance work for muscle. Start where you are and build. On injection days with early side effects, lighter movement still counts. Exercise also protects against regain if you later stop treatment¹³.

No supplement is required with Mounjaro, but eating much less can leave gaps, so a standard daily multivitamin is a reasonable safety net while losing weight. Discuss anything beyond that with a pharmacist. Supplements sold as natural GLP-1 boosters are not equivalents and are not substitutes for prescribed treatment. Oral supplements, like other oral products, may be absorbed more slowly when you start treatment.

08 · What trials show

What the trials show about diet and results

Trial results come from treatment used with diet and exercise, not from the medicine alone. 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 alone².

Trial averages do not predict your own result, and they do not set a calorie target for you. They show that the diet and activity part of the plan is built in.

09 · NHS and next steps

NHS access and who sets your plan

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 conditions⁴⁶. Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment.

With us, ongoing monthly reviews, dose-titration and follow-up assessments are carried out by the prescribing team, with side-effect support. That is the right place to raise worries about appetite and intake. 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. Related reading: calories while on Mounjaro and how many calories to have on Mounjaro.

10 · Plateaus and tracking

If your weight stalls

A stall does not mean the medicine has stopped working. Check the common leaks first: liquid calories, grazing, larger portions as appetite returns between doses, and reduced activity. Weigh and measure for a short stretch so you are working from facts, not feelings.

Tracking helps. Our free GLPTrackr companion app lets you log your GLP-1 journey on iOS or Android. Bring your notes to your monthly review so the prescribing team can see the pattern.

Equally, do not respond to a plateau by cutting food to an extreme. Eating far less rarely fixes it and makes muscle loss, tiredness and nutritional gaps more likely. For a week-by-week view, see how many calories to eat on Mounjaro in the early weeks, and how many calories a day to have.