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 While Taking Mounjaro
When starting Mounjaro (tirzepatide), many people find their appetite naturally decreases and relationship with food changes significantly. This guide explains what to eat, foods to avoid, how to manage common digestive side effects, and why your dietary needs may differ from those taking Wegovy. Always consult your GP or prescriber for personalised dietary advice, especially if you have existing health conditions or take other medications. Use our GLP-1 weight loss calculator above to understand how dietary changes support your Mounjaro treatment.
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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.
Dietary Approach While Taking Mounjaro
Mounjaro works by reducing hunger signals and slowing gastric emptying—how quickly food leaves your stomach. This means many people naturally eat smaller portions and feel satisfied sooner. Focus on protein-rich, nutrient-dense foods that provide sustained energy on smaller portions: lean meats, fish, eggs, Greek yoghurt, beans, and pulses.
- High-protein options: chicken, turkey, salmon, cottage cheese, tofu, lentils, chickpeas
- Low-calorie vegetables: broccoli, spinach, courgettes, peppers, tomatoes—bulk meals without excess calories
- Healthy fats: avocado, olive oil, nuts, seeds—nutrient-dense despite small quantity
- Whole grains: brown rice, oats, quinoa—in smaller portions than usual
Drink plenty of water throughout the day. Dehydration can worsen nausea and constipation, both common side effects. Sip slowly rather than drinking large amounts at once. Many people find staying hydrated helps manage appetite and supports weight loss alongside Mounjaro dose titration.
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.
Foods To Avoid and Managing Digestive Side Effects
Avoid or limit: high-fat foods (fried foods, fast food, rich sauces), sugary items (cakes, sweets, sugary drinks), alcohol, and spicy foods—these can trigger nausea and stomach discomfort on Mounjaro. Caffeine may also worsen nausea in some people, especially when taken on an empty stomach.
Nausea is very common during initial doses and dose escalation phases. Eat slowly, chew thoroughly, and eat smaller amounts more frequently. If nausea persists, mention this to your prescriber—they may adjust your Mounjaro kwikpen schedule or recommend anti-nausea strategies. Constipation is also common; increase fibre gradually, drink more water, and discuss options with your GP. Track your dietary changes and symptoms using our free progress tracker to identify what works best for your body.
- 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.
Is the diet different if I'm taking Mounjaro versus Wegovy?
Both Mounjaro (dual GIP+GLP-1 agonist) and Wegovy (GLP-1 agonist only) reduce appetite similarly, so dietary principles are very similar—protein-rich, smaller portions, nutrient-dense foods. However, individual responses vary. Some people on Mounjaro report slightly different digestive patterns because of its dual mechanism. Your prescriber can advise whether your specific response requires dietary adjustments. Both work alongside a reduced-calorie diet.
How much should I eat while taking Mounjaro?
There's no set amount—Mounjaro itself regulates appetite signalling. Most people eat naturally smaller portions because they feel fuller sooner. Listen to your body's hunger cues. If you're losing weight too quickly (more than 1 kg per week sustained), eat slightly more nutrient-dense food. If you're not losing weight as expected, your prescriber may review your dose or dietary pattern. Our GLP-1 weight loss calculator can help you understand realistic projections.
Will I need to count calories on Mounjaro?
Not necessarily. The appetite-suppressing effects of Mounjaro often naturally create a calorie deficit without strict counting. However, some people find tracking helpful initially to understand portion sizes and ensure adequate nutrition. Your prescriber or a registered dietitian can advise. Remember, Mounjaro works best alongside a reduced-calorie diet and increased physical activity—it's not a replacement for lifestyle changes.
What if I feel sick while eating on Mounjaro?
Nausea is common, especially during dose escalation. Try eating softer, blander foods like porridge, soup, scrambled eggs, or mashed vegetables. Eat very slowly in small amounts. Avoid high-fat and spicy foods. Stay hydrated with sips of water. If nausea is severe or persistent, contact your GP or prescriber—they may recommend anti-nausea medication or pause dose escalation temporarily. Nausea often improves after a few weeks at each dose level.
Can I follow a specific diet (keto, vegan, Mediterranean) on Mounjaro?
Yes, you can follow most dietary patterns on Mounjaro. Mediterranean diet is recommended by NHS for general health and supports sustainable weight loss. Vegan or vegetarian diets work well—focus on plant-based proteins like beans, lentils, tofu, and nuts. Very low-carb diets (keto) are possible but discuss with your prescriber, especially if you have diabetes, as Mounjaro affects blood sugar. Ensure you're meeting nutritional needs across whichever pattern you choose.
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.