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 to Eat When Taking Mounjaro
When you start Mounjaro (tirzepatide), your appetite naturally decreases, making meal planning easier but requiring thoughtful food choices. Getting the right nutrition matters just as much as portion control. This guide explains how to eat well alongside Mounjaro treatment, including practical meal ideas, foods to favour, and how to manage side effects through diet. Your GP or prescriber can offer personalised dietary advice tailored to your health.
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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.
Meals and Foods That Work Well With Mounjaro
Mounjaro works best when combined with a balanced, reduced-calorie diet. Many people find their appetite naturally suppressed, so smaller portions feel satisfying. Focus on nutrient-dense foods that pack nutrition into smaller amounts: lean proteins (chicken, fish, eggs), non-starchy vegetables (broccoli, spinach, peppers), and whole grains in moderation. Avoid highly processed foods, sugary drinks, and fatty meals — these can trigger nausea or stomach discomfort, especially in the first weeks of treatment. Eating slowly and chewing thoroughly helps you notice fullness sooner. Protein is particularly important — aim for 25–30g per meal to preserve muscle mass during weight loss. Stay hydrated with water throughout the day. If certain foods trigger side effects, keep a simple food diary to identify patterns. Your progress tracker can help you log not just weight but also how different meals make you feel.
- Lean proteins: chicken breast, fish, turkey, tofu
- Vegetables: broccoli, leafy greens, carrots, courgettes
- Whole grains: oats, brown rice (small portions)
- Healthy fats: olive oil, avocado, nuts (measured amounts)
- Low-sugar fruits: berries, apples
Clinically BackedWeight Loss
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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.
Managing Side Effects Through Diet Choices
Nausea, constipation, and indigestion are common side effects, especially during the first 4 weeks and after dose increases. Dietary adjustments can help significantly. For nausea: eat smaller, more frequent meals rather than three large ones; ginger tea or peppermint can help; avoid greasy or spicy foods. For constipation: increase fibre gradually (not suddenly, as this can worsen stomach discomfort), drink more water, and include cooked vegetables. For indigestion: eat slowly, avoid lying down immediately after meals, and limit caffeine. As side effects typically settle after a few weeks, most people find they can return to a wider variety of foods. Mounjaro vs Wegovy — both are GLP-1 medications with similar dietary needs, though individual tolerance varies. If side effects persist beyond 4 weeks, speak to your GP or prescriber rather than restricting your diet too severely.
- 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.
What should I eat in the first week of starting Mounjaro?
Focus on bland, easily digestible foods: plain chicken, white rice, mashed sweet potato, and leafy greens. Keep meals small and frequent. Avoid fried foods, caffeine, and anything with strong spices. Sip water throughout the day. Most people find nausea settles after a few days as the body adjusts.
Can I eat normal-sized meals on Mounjaro?
Most people find they can't — and don't need to. Mounjaro triggers fullness signals, so normal portions feel oversized. Smaller portions (typically 50–75% of your usual meal size) satisfy hunger. This is actually beneficial for weight loss alongside reduced-calorie intake. Eat when genuinely hungry, stop when full.
How does Mounjaro affect how much I should eat?
Mounjaro suppresses appetite naturally, so your body needs fewer calories to feel satisfied. Combined with a reduced-calorie diet (typically 500–800 calories below your maintenance), this creates the deficit needed for weight loss. Your prescriber can advise on a safe calorie target for your individual health and goals.
Is there a specific "Mounjaro diet" I must follow?
No single diet works for everyone. What matters is eating nutritious foods in smaller portions with a calorie deficit. Mediterranean-style eating (vegetables, lean proteins, whole grains) is well-supported by evidence. The key is finding foods you enjoy that don't trigger side effects and that fit your lifestyle long-term.
Can I use our GLP-1 weight loss calculator to plan my meals?
The calculator helps project weight loss at different Mounjaro doses, which can guide your dietary calorie targets. Combine this with our BMI calculator and progress tracker to monitor your health metrics and see how dietary choices affect your results over time. Track both weight and how you feel.
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.