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 Should I Eat On Mounjaro?
When you start taking Mounjaro (tirzepatide), your appetite naturally decreases, and you may find you feel fuller after smaller meals. There's no strict "Mounjaro diet" — instead, focus on nutritious, easily digestible foods that won't trigger nausea or stomach discomfort. Your GP or the prescriber managing your treatment can provide personalised dietary guidance, but here's what works well for most people taking this prescription weight loss 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.
Best Foods to Eat While Taking Mounjaro
Protein is essential — aim for lean sources like chicken, fish, eggs, Greek yoghurt, and legumes. Protein helps preserve muscle during weight loss and keeps you satisfied longer. Vegetables and whole grains provide fibre and nutrients without excessive calories. Start with small portions and eat slowly, allowing time to recognise fullness signals.
- Lean proteins: chicken breast, white fish, turkey, cottage cheese
- Vegetables: broccoli, spinach, carrots, courgettes, peppers (cooked or raw)
- Whole grains: oats, brown rice, wholemeal bread (in small amounts)
- Healthy fats: avocado, olive oil, nuts (in portion-controlled amounts)
- Low-sugar fruits: berries, apples, oranges
Stay hydrated throughout the day — dehydration is common on Mounjaro and can worsen nausea. Sip water regularly rather than drinking large amounts at once.
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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 Avoid or Limit on Mounjaro
Fatty, greasy, and high-sugar foods often trigger nausea and stomach discomfort on Mounjaro. These include fried foods, full-fat dairy, sugary snacks, and processed meals. Alcohol may also increase nausea — discuss this with your prescriber. Caffeine on an empty stomach can worsen digestive symptoms.
- Avoid: fried foods, fatty cuts of meat, heavy creamy sauces
- Limit: refined carbohydrates, biscuits, cakes, sweets
- Be cautious: spicy foods (may irritate the stomach)
- Monitor: caffeine intake, especially if nausea is present
If you're unsure whether a food will suit you, start with a small portion and observe how you feel. Track your symptoms using our free progress tracker 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.
Can I eat normally while taking Mounjaro?
No — Mounjaro significantly reduces appetite, so you'll naturally eat much smaller portions. This is the medication's intended effect. You may find that normal meal portions feel uncomfortably large. Focus on nutrient-dense foods in smaller quantities rather than trying to eat your usual amounts.
Will I get nausea if I eat certain foods on Mounjaro?
Yes — fatty, greasy, and high-sugar foods commonly trigger nausea in people taking Mounjaro. Nausea is a very common side effect, especially in the first few weeks. If nausea persists beyond the first few weeks, discuss it with your prescriber — dose adjustment or management strategies may help.
Do I need to follow a specific diet plan while on Mounjaro?
There's no official "Mounjaro diet" required by prescription. However, eating whole foods, lean proteins, vegetables, and staying hydrated works best for most people. Your GP or prescriber can refer you to a dietitian for personalised guidance tailored to your health needs and preferences.
How much should I eat per meal on Mounjaro?
Portion sizes vary by individual, but most people find they eat significantly less — often only 25–50% of their usual meal size. Start with small portions and eat slowly, stopping when you feel full. You may need to experiment to find what's comfortable for you on your current dose.
Is it safe to take Mounjaro with alcohol?
Alcohol can increase nausea and stomach discomfort while taking Mounjaro. Limit alcohol intake and discuss safe consumption with your prescriber. Some people find they tolerate small amounts of light alcohol, while others experience worsening symptoms — individual responses vary.
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.