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
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What Not to Eat on Mounjaro
When taking Mounjaro (tirzepatide), certain foods may worsen side effects like nausea, bloating, and stomach discomfort. While Mounjaro doesn't ban specific foods, understanding which foods to limit can help you feel better and get the most from your treatment. This guide covers practical food choices and eating patterns that work well alongside Mounjaro therapy. As always, consult your GP or prescriber if you have concerns about your diet while taking this prescription-only injection.
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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.
Foods and Eating Patterns to Limit on Mounjaro
High-fat and greasy foods are often the first foods people find difficult on Mounjaro. Your stomach empties more slowly when taking tirzepatide, which can cause nausea, bloating, and discomfort if you eat fatty meals. Fried foods, butter-heavy dishes, fatty cuts of meat, and full-fat dairy products may trigger these side effects.
Sugary and ultra-processed foods tend to be less satisfying on Mounjaro because the medication suppresses appetite signals. Sweets, sugary drinks, pastries, and processed snacks may also cause rapid blood sugar spikes followed by crashes, leaving you feeling worse. These foods offer little nutritional value and don't help you feel full.
Eating patterns to avoid: large meals, eating too quickly, and not chewing thoroughly often lead to discomfort. Mounjaro users typically feel fuller on smaller portions, so three large meals may be harder to manage than five or six smaller ones.
Alcohol, particularly on an empty stomach, may amplify nausea and dizziness—common Mounjaro side effects. Limit alcohol intake and always eat something when drinking.
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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.
Practical Food Choices That Work Better on Mounjaro
Focus on lean proteins, whole grains, and plenty of vegetables. Grilled chicken, fish, beans, lentils, and tofu are easier to digest and keep you satisfied longer. Low-fat Greek yoghurt, eggs, and cottage cheese are also well-tolerated. Wholemeal bread, oats, brown rice, and quinoa provide sustained energy without the blood sugar spikes.
Eat slowly and mindfully—take at least 20–30 minutes per meal and chew thoroughly. Drink water between meals rather than with food to avoid feeling overly full. Ginger tea, peppermint tea, and clear broths may help settle your stomach. If nausea persists, try eating smaller amounts more frequently throughout the day rather than three large meals.
Try our GLP-1 weight loss calculator to see how Mounjaro may support your weight management journey when combined with these dietary changes. Our free progress tracker can also help you log what you eat and how you feel, identifying which foods work best for you personally.
- 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 normally on Mounjaro, or do I have to avoid certain foods?
You don't have to avoid specific foods entirely, but high-fat, greasy, and sugary foods often trigger nausea and bloating because Mounjaro slows stomach emptying. Most people naturally eat less of these foods and feel better focusing on lean proteins, vegetables, and whole grains. Your appetite suppression makes portion control easier.
Will eating the wrong foods on Mounjaro make it not work?
No, the wrong foods won't stop Mounjaro working—tirzepatide acts at the hormone level regardless of diet. However, eating high-fat meals may cause unpleasant side effects like nausea and discomfort. Eating nutritious, smaller portions alongside your Mounjaro prescription helps you feel better and supports your weight loss goals more effectively.
Is it safe to drink alcohol while taking Mounjaro?
Alcohol is generally safe in moderation, but it may worsen nausea, dizziness, and other common Mounjaro side effects—especially on an empty stomach. If you choose to drink, always eat something first and limit intake. Always ask your GP or prescriber if you have concerns about alcohol and your specific health.
How soon after starting Mounjaro will I feel less hungry?
Most people notice reduced appetite within the first few weeks of starting Mounjaro, especially as doses increase toward 5 mg and beyond. However, individual timelines vary. Your prescriber will help you titrate (gradually increase) your dose over several weeks to find your effective level while managing side effects.
Should I follow a specific diet while taking Mounjaro, like a low-carb or low-fat diet?
There's no single "best" diet for Mounjaro users. Focus on sustainable, balanced eating with lean proteins, vegetables, and whole grains—the key is eating less overall because appetite is naturally reduced. Your GP or a registered dietitian can give you personalised dietary advice based on your health, preferences, and any existing conditions like type 2 diabetes.
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.