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 While Taking Mounjaro
When you start taking Mounjaro (tirzepatide), your relationship with food changes significantly. This prescription-only injection may help reduce your appetite and food cravings, but it also means nausea and digestive changes are common, especially during the first few weeks. Understanding what to eat—and what to avoid—can help you manage side effects while supporting sustainable weight loss. Your GP or prescriber should provide dietary guidance as part of your treatment plan, but here's practical information about eating while using this medication.
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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.
Foods and Eating Strategies While Taking Mounjaro
As a dual GIP and GLP-1 receptor agonist, Mounjaro slows how quickly food moves through your stomach and signals fullness to your brain. This means smaller portions feel satisfying, but it also increases nausea risk—especially in the first 4 weeks on each dose.
Best foods to eat while taking Mounjaro:
- Light, easily digestible proteins: chicken breast, fish, eggs, Greek yoghurt, cottage cheese
- Non-starchy vegetables: broccoli, spinach, courgettes, peppers, green beans
- Whole grains in small amounts: oats, brown rice, quinoa
- Low-sugar fruits: berries, apples (eat slowly, in small portions)
- Healthy fats: olive oil, avocado, nuts (though often in smaller quantities than before)
Eating tips: Eat slowly and chew thoroughly. Drink plenty of water throughout the day. Eat smaller, frequent meals rather than three large meals. Avoid eating too quickly after taking your weekly injection.
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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.
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Foods to Avoid and Managing Nausea
Foods that often trigger nausea with Mounjaro: Greasy or fried foods, high-sugar foods and drinks, very spicy foods, heavy red meats, dairy products (if you're sensitive), and carbonated beverages. Nausea is a very common side effect in the first few weeks—it typically improves as your body adjusts to each dose.
If nausea persists, try eating blander foods: plain toast, crackers, mashed potato, soup broths, or rice cakes. Stay hydrated with water, herbal tea, or low-sugar electrolyte drinks. If nausea is severe or you're struggling to eat enough, contact your GP. Some people benefit from ginger tea or eating smaller amounts more frequently. Remember: there's no "perfect" diet with Mounjaro—what matters is finding foods that you tolerate well and that support a calorie deficit when combined with the medication's appetite-reducing effects.
- 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?
Your appetite will likely be significantly reduced, so portion sizes will naturally decrease. You may find you feel uncomfortably full after eating much less than before. This is the medication working as intended. Focus on nutrient-dense foods rather than eating "normal" amounts—listen to your body's fullness signals and stop eating when satisfied, not when your plate is empty.
Is there a specific diet I should follow with Mounjaro?
There's no single "Mounjaro diet." However, eating protein-rich foods, plenty of vegetables, and drinking water supports both the medication's effects and your overall health. A reduced-calorie diet (typically 500 kcal below your maintenance level) combined with Mounjaro supports weight loss. Your prescriber or a registered dietitian can provide personalised guidance based on your health needs.
What if I'm vomiting or too nauseous to eat?
Mild nausea is common in the first 4 weeks on each dose and usually improves. Try eating smaller amounts more frequently, stick to bland foods, and stay hydrated. However, if you're vomiting persistently or unable to eat enough to meet basic nutritional needs, contact your GP. They may suggest adjusting your dose or exploring management strategies. Severe nausea isn't something you should endure—medical support is available.
Can I drink alcohol while taking Mounjaro?
Yes, but with caution. Alcohol may increase nausea and slow gastric emptying further, and it adds empty calories without nutritional value. If you do drink, do so with food, keep portions small, and stay well hydrated. Some people find they tolerate alcohol less well while taking Mounjaro. Your GP can advise based on your individual health profile.
Should I track calories while taking Mounjaro?
Calorie awareness can be helpful, especially early on, since the medication supports—but doesn't assures—weight loss. However, many people find portion control naturally happens because they feel fuller faster. Use our free GLP-1 weight loss calculator to get an estimate of potential results, and consider tracking your progress with our progress tracker to monitor what's working for you alongside dietary changes.
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.