The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
What Food Should You Eat While Taking Mounjaro?
When you start Mounjaro (tirzepatide), your appetite naturally decreases, which means choosing the right foods becomes more important for maintaining good nutrition. This NHS-aligned guide explains what to eat while on Mounjaro, how to manage side effects like nausea and constipation, and practical meal ideas that work with how the medication changes your relationship with food. Always consult your GP or the specialist prescribing your Mounjaro for personalised dietary advice alongside your treatment plan.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Nutrition Strategy While On Mounjaro Treatment
While taking Mounjaro, your body needs fewer calories but not fewer nutrients. Focus on nutrient-dense foods that provide vitamins, minerals, and protein in smaller portions. The NHS recommends prioritising: lean proteins (chicken, fish, eggs, Greek yoghurt), non-starchy vegetables (broccoli, spinach, peppers, courgettes), whole grains in moderation, and healthy fats (olive oil, avocado, nuts).
Because Mounjaro slows gastric emptying, eat slowly and chew thoroughly. Small, regular meals work better than large ones — many people find 3–4 smaller meals more manageable than traditional large portions. Stay hydrated with water and herbal tea, as dehydration can worsen nausea. Avoid high-fat, greasy foods and very sugary items, as these can trigger side effects. Your GP or NHS dietitian can assess your individual needs and suggest specific meal plans aligned with your health goals and the dose titration schedule.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Managing Side Effects Through Food Choices
Nausea and constipation are common when starting Mounjaro or increasing your dose. To manage nausea, eat bland foods like toast, rice, crackers, and boiled potatoes — avoid strong flavours and spicy dishes initially. Ginger tea, lemon water, and small portions of soup may help settle your stomach. For constipation, increase fibre gradually through vegetables, fruits, beans, and whole grains, and drink plenty of water. Don't jump to high-fibre suddenly, as this can worsen bloating. If side effects persist beyond a few weeks or significantly affect your nutrition, contact your GP. Use our free GLP-1 weight loss calculator to track how your eating patterns change, and our progress tracker to monitor your overall wellbeing alongside dietary adjustments.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Can I eat normal food while on Mounjaro?
Yes, you can eat normal foods, but in much smaller portions. Mounjaro reduces appetite naturally, so you'll feel satisfied with less. Choose nutrient-rich foods to ensure you're getting enough vitamins and minerals despite smaller amounts. Your GP can advise if you have specific dietary needs or health conditions.
What foods should I avoid while taking Mounjaro?
Avoid very fatty, greasy, and highly processed foods, as these can trigger nausea and stomach discomfort. Limit sugary drinks and sweets. Alcohol may cause nausea or low blood sugar. Spicy foods and very hot meals can worsen gastrointestinal side effects, especially in the first few weeks.
How much should I eat each day on Mounjaro?
There's no fixed amount — hunger cues change with Mounjaro. Eat when you're genuinely hungry and stop when satisfied. Most people naturally consume 500–1000 fewer calories daily without conscious restriction. Your prescriber or NHS dietitian can give personalised guidance based on your health goals.
Will I get enough nutrition on Mounjaro with smaller portions?
Yes, if you choose nutrient-dense foods: proteins, leafy greens, whole grains, and healthy fats. A smaller volume of nutritious food provides more nutrients than a larger volume of processed food. If concerned about deficiencies, ask your GP about vitamin supplementation or dietitian referral.
Does Mounjaro interact with specific foods?
Mounjaro doesn't interact directly with foods, but it may reduce absorption of some oral medications. Separate medication doses from meals where advised by your prescriber. High-fat meals may slow medication absorption further, so moderate fat intake around the time you take other medications.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.