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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Best Diet to Use With Mounjaro in the UK
Mounjaro (tirzepatide) is most effective when combined with a reduced-calorie diet and increased physical activity — medication alone won't produce sustainable weight loss. This guide explains the best dietary approach to support Mounjaro treatment, based on NHS nutritional guidance and clinical trial evidence. Whether you're accessing Mounjaro through NHS specialist services or privately, pairing it with the right eating pattern maximises results and helps you maintain weight loss long-term.
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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.
Dietary Approach When Taking Mounjaro
Mounjaro works best alongside a reduced-calorie, balanced diet. Clinical trials showed that medication combined with lifestyle changes produced significantly better results than medication alone. The NHS recommends aiming for a calorie deficit of approximately 500 kcal per day, which typically results in weight loss of around 0.5–1 kg per week.
Key dietary principles with Mounjaro:
- Focus on protein-rich foods — lean meat, fish, eggs, dairy, legumes — to preserve muscle mass during weight loss
- Eat plenty of vegetables and whole grains to maintain fibre intake and satiety
- Limit highly processed foods, sugary drinks, and foods high in fat and calories — Mounjaro makes you feel fuller, but calorie quality still matters
- Stay hydrated — drink water regularly throughout the day
- Eat slowly and mindfully — Mounjaro slows gastric emptying, so smaller, slower meals work better than large meals
- Avoid foods that trigger nausea if you experience gastrointestinal side effects
Many people find portion sizes reduce naturally when taking Mounjaro due to increased fullness signals. Use this to your advantage, but focus on nutritious foods rather than empty calories. Try our free GLP-1 weight loss calculator to project potential results at different Mounjaro doses alongside dietary changes.
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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.
Foods to Favour and Limit With Mounjaro
Foods that work well with Mounjaro: grilled fish and chicken, Greek yoghurt, eggs, beans and lentils, broccoli and leafy greens, sweet potatoes, oats, berries, and nuts in moderation. These are nutrient-dense and keep you fuller longer.
Foods to limit or avoid: fried foods, sugary snacks and desserts, full-fat dairy, alcohol (especially early in treatment), and large portions. These can trigger nausea, undo calorie deficits, or slow weight loss.
The Mediterranean diet pattern aligns well with Mounjaro treatment — emphasising olive oil, fish, vegetables, and whole grains — and has strong NHS evidence for long-term health benefits. Consider working with your GP or a registered dietitian for personalised guidance, especially if you have type 2 diabetes or other comorbidities alongside your weight management journey.
- 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 while taking Mounjaro?
You can eat normal foods, but portions typically reduce naturally due to increased fullness from Mounjaro. The medication works best when paired with a reduced-calorie diet — aim for roughly 500 kcal below your normal intake. Focus on nutritious, protein-rich foods rather than calorie-dense options.
What should I do if Mounjaro gives me nausea around food?
Nausea is very common, especially in the first few weeks. Eat smaller, more frequent meals, avoid fatty or greasy foods, stay hydrated with water and herbal teas, and eat slowly. Ginger tea may help. If nausea persists beyond 4 weeks, contact your prescriber — dose adjustment may be needed.
Do I need to follow a specific diet plan with Mounjaro?
No specific branded diet is required. The NHS recommends a balanced, reduced-calorie approach with plenty of vegetables, lean protein, and whole grains. A registered dietitian can provide personalised advice, especially if you have diabetes or other health conditions. Your prescriber can refer you to dietetic support.
How quickly will I see weight loss if I diet with Mounjaro?
Results vary between individuals. Clinical trials showed average weight loss of 15–21% body weight over 72 weeks when Mounjaro was combined with diet and exercise. Sustainable loss is typically 0.5–1 kg per week. Use our free progress tracker to monitor your journey.
Is Mounjaro available on the NHS for weight management?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use through specialist tier 3 weight management services. Eligibility includes BMI ≥30, or BMI 27–29.9 with weight-related conditions. Access varies significantly by region and availability. Discuss referral options with your GP.
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.