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 Should You Eat On Mounjaro?
If you're taking Mounjaro (tirzepatide), eating the right foods can help you manage side effects and support your weight loss goals. This UK health guide explains what to eat, how to adjust your diet as your dose titration progresses, and practical strategies for managing appetite changes. Remember, Mounjaro is a prescription-only medicine, and dietary advice should be personalised—your GP or prescriber can give you guidance specific to your health needs.
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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.
Diet and Nutrition on Mounjaro — What Works Best
Mounjaro works best alongside thoughtful dietary choices. Many people taking this GLP-1 receptor agonist find that smaller portions feel satisfying due to reduced appetite. Focus on protein-rich foods — lean chicken, fish, eggs, Greek yoghurt, and pulses — which help maintain muscle mass during weight loss and promote satiety. Include whole grains, vegetables, and healthy fats from olive oil, avocados, and nuts.
- Eat slowly and chew thoroughly—your stomach empties more slowly on Mounjaro
- Drink plenty of water to manage constipation, a common side effect
- Avoid high-fat, greasy foods which can worsen nausea and gastrointestinal discomfort
- Limit sugar and ultra-processed foods—they offer little nutritional benefit alongside reduced appetite
- Spread meals across the day rather than eating large portions at once
As your Mounjaro KwikPen dose increases during dose titration, you may experience nausea or reduced appetite. This is normal. Small, frequent meals of nutrient-dense foods help you stay nourished without triggering side effects. Work with a registered dietitian if available through your GP or NHS referral pathway.
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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.
Accessing Mounjaro in the UK — Costs and Eligibility
Mounjaro eligibility in the UK requires a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Two routes are available: NHS specialist services or private prescription. NHS access involves referral to a tier 3 weight management service through your GP, though waiting lists vary significantly by region. Our free BMI calculator can help you check if you fall within eligibility thresholds. Private online consultations with UK-licensed prescribers typically cost £30–£50, and medication costs range from £129–£320 per month depending on your dose. Both routes require clinical assessment to ensure safety and suitability.
- 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.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs vary between providers, typically ranging from £129 to £320 per month depending on your dose. Starting doses (2.5 mg) are usually at the lower end, while maximum doses (15 mg) cost more. Online prescriptions typically incur a separate consultation fee (£30–£50). NHS access is free but involves a waiting list and specialist referral.
What foods should I avoid on Mounjaro?
Avoid high-fat, fried, and greasy foods which can trigger nausea and gastrointestinal side effects. Limit sugary foods, alcohol, and very large meals. Foods high in fibre may worsen diarrhoea initially, though this often settles. Focus on lean proteins, vegetables, and whole grains instead. Eat slowly and in smaller portions.
Can I get Mounjaro through the NHS in the UK?
Yes—Mounjaro is NICE-approved for NHS use through specialist tier 3 weight management services. You'll need a GP referral and clinical assessment. Availability and waiting times vary significantly by region and ICB. Private prescription is an alternative route if NHS waiting lists are lengthy in your area.
How does Mounjaro compare to Wegovy for managing diet?
Both are GLP-1 medications that reduce appetite, but Mounjaro uses dual GIP and GLP-1 action versus Wegovy's GLP-1 only. Clinical trials show Mounjaro may produce slightly greater average weight loss (~20% vs ~15% body weight). Both work best with reduced-calorie diets and increased activity. Individual results vary, and your prescriber will advise which suits you.
Should I change my diet when my Mounjaro dose increases?
Yes—as your KwikPen dose increases during titration, appetite suppression typically increases. You may need to eat smaller portions or more frequent meals. Stay hydrated, prioritise protein, and monitor side effects like nausea or constipation. Keep your prescriber informed of any severe changes so they can adjust your dose or provide additional support.
Ready to take control of your weight loss journey?
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