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 to Eat on Mounjaro — NHS UK Guidance
When you start Mounjaro (tirzepatide) through an NHS specialist weight management service, dietary changes are as important as the medication itself. There's no single "Mounjaro meal plan" — instead, your NHS tier 3 service will work with you to develop an eating approach tailored to your individual needs, medical history, and preferences. This guide covers practical food choices, portion management, and what to expect nutritionally while taking Mounjaro in the UK.
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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.
How Mounjaro Changes Your Relationship With Food
Mounjaro (tirzepatide) works by activating GIP and GLP-1 pathways, which signals your brain that you're full sooner and reduces appetite. This means you'll likely eat less naturally without feeling deprived — but your actual meal plan should focus on nutritional quality, not restriction.
Your NHS prescriber or dietitian will typically recommend:
- Protein at every meal — lean meat, fish, eggs, yoghurt, beans — to preserve muscle during weight loss and keep you full longer
- Non-starchy vegetables — broccoli, spinach, peppers, courgettes — for fibre and nutrients without excess calories
- Whole grains and legumes — oats, brown rice, lentils — if tolerated (some people experience nausea initially)
- Healthy fats in small amounts — olive oil, avocado, nuts — important for hormone health and nutrient absorption
Early on, you may experience nausea, reduced appetite, or changes in food preferences — these side effects are temporary as your body adjusts. Your GP or NHS dietitian can support you through this transition.
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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 Eating Tips When Taking Mounjaro
Start with smaller portions — you'll feel full faster, which is the medication working as intended. Eat slowly, chew well, and stop when comfortably full rather than overfull. Stay hydrated (aim for 6–8 glasses of water daily) as this helps manage any nausea and supports weight loss.
Avoid or minimise high-fat, greasy foods, sugary drinks, and large meals — these can trigger stomach discomfort or nausea while on Mounjaro. Many people find that ultra-processed foods become less appealing naturally. If food aversions occur, swap temporarily for alternatives you tolerate, then reintroduce gradually. Use our free weight loss calculator alongside your NHS plan to track projected progress, and log actual meals in a food diary if recommended by your dietitian to identify patterns.
- 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.
Do I need a special diet when taking Mounjaro on the NHS?
No single "Mounjaro diet" exists. Your NHS tier 3 dietitian or GP will advise dietary changes tailored to you. Generally, focus on whole foods, adequate protein, vegetables, and smaller portions — the medication itself reduces hunger, so restriction isn't necessary. Your prescriber may refer you to a registered dietitian for personalised guidance.
Can I eat normally on Mounjaro?
Yes, but your appetite will likely be lower. You'll naturally eat less and feel fuller faster. Nausea in the first few weeks may limit what feels appealing — this is temporary. Most people return to eating a wide variety of foods after the initial adjustment period, though portions remain smaller.
What if I experience nausea or food aversions on Mounjaro?
Nausea is common, especially in weeks 1–4 and after dose increases. Stick to bland, easily digestible foods — toast, crackers, clear broths, plain chicken. Avoid greasy or heavy meals. Sip water throughout the day. Contact your NHS prescriber if nausea persists beyond a few days or prevents you eating adequately — they may slow your dose escalation.
How does Mounjaro fit with calorie counting?
Formal calorie counting isn't always necessary because Mounjaro reduces hunger and portion size naturally. However, some people find food diaries helpful for understanding eating patterns. Your NHS dietitian can advise whether tracking is useful for you personally. Focus on food quality over strict calorie limits.
Will my meal plan change as my Mounjaro dose increases?
Your appetite and side effects may change at each dose increase. Early weeks tend to involve more nausea and reduced appetite; this often settles. Your NHS provider should review your eating and any nutritional concerns at each appointment. They may adjust dietary recommendations as your tolerance improves and doses increase.
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.