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 Foods Can You Eat on Mounjaro?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) work by reducing appetite and making you feel fuller after smaller meals — but there are no specific foods you must avoid or can only eat. However, certain foods may cause discomfort due to how these medications affect digestion. Understanding what works best for your body, alongside your prescriber's guidance, helps you get the most from treatment while minimising side effects.
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Calculate Your BMI Instantly
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.
Food Considerations on Mounjaro vs Wegovy
Both medications work the same way with food: they don't restrict what you eat, but they change how your body processes it. The key difference lies in their mechanism — Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1 agonist only. This dual action in Mounjaro may mean some users experience different digestive responses to foods.
- High-fat foods: May cause nausea, stomach discomfort, or diarrhoea on either medication, particularly at higher doses
- Sugary foods: Often less appealing naturally — appetite suppression reduces cravings
- Large meals: Slowed gastric emptying means food stays in your stomach longer, so smaller portions feel more satisfying
- Spicy or acidic foods: May trigger reflux or indigestion, especially in the first weeks of dose titration
The SURMOUNT trial data for Mounjaro and STEP trials for Wegovy both showed that successful weight loss combined medication with a reduced-calorie diet and increased physical activity — not specific food restrictions.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 Food and Digestion: Practical Tips
Start with small, frequent meals rather than three large ones. Focus on lean proteins, vegetables, whole grains, and foods low in saturated fat — this approach often minimises nausea and discomfort. Stay hydrated; many people on GLP-1 or tirzepatide forget to drink enough water, which worsens constipation (a common side effect).
If you experience persistent nausea or indigestion after certain foods, keep a simple food diary for a week. This helps identify your personal triggers — everyone responds differently. Your prescriber or a registered dietitian can offer personalised guidance tailored to your UK weight management plan. Use our free GLP-1 weight loss calculator to track how dietary changes support your progress alongside medication.
- 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.
Are there foods I absolutely cannot eat on Mounjaro?
No — Mounjaro (tirzepatide) doesn't forbid any foods. However, high-fat, greasy, or very sugary foods may trigger nausea, stomach pain, or diarrhoea, especially at higher doses during dose titration. Your prescriber will advise based on your individual response.
Does Mounjaro work differently with food than Wegovy?
Both medications reduce appetite and slow digestion. Mounjaro's dual GIP and GLP-1 mechanism may cause different digestive responses in some people compared to Wegovy's single GLP-1 action, but food restrictions are identical — there are none, only tolerance considerations.
Will I naturally eat less on Mounjaro?
Yes — both medications signal fullness to your brain. Most people on the KwikPen find portion sizes naturally decrease. You'll feel satisfied after smaller meals, which supports the calorie deficit needed for weight loss without conscious restriction.
Can I drink alcohol on Mounjaro?
Yes, but with caution. Alcohol on an empty stomach (which you're less likely to have due to reduced appetite) may cause nausea. Drink with food, stay hydrated, and be aware that alcohol slows gastric emptying further, potentially worsening side effects.
What if I get nausea from foods on Mounjaro?
Nausea is very common, especially in weeks 1–8 during dose escalation. Stick to bland, easily digestible foods — boiled chicken, rice, toast, bananas. Eat slowly and in smaller portions. If nausea persists beyond 2–3 weeks, contact your prescriber; dose adjustments may help.
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.