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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Diet Plan On Mounjaro: Nutrition Guidance for UK Adults
If you're taking Mounjaro (tirzepatide), your appetite and food preferences will likely change significantly. This guide explains how to plan your diet effectively while on this GLP-1 and GIP receptor agonist medication, including practical nutrition tips, what to eat, and how to maintain balanced meals despite reduced hunger. Mounjaro works by signalling to your brain that you're full, which means you'll naturally eat less — but planning your nutrition carefully ensures you're still getting the nutrients your body needs. Use our free GLP-1 weight loss calculator to project your potential results while following a balanced diet plan.
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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.
How Mounjaro Changes Your Appetite and Food Intake
Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways that regulate appetite and satiety. When you start taking this tirzepatide injection, you'll likely notice you feel full much faster, experience reduced cravings, and find large meals unappetising. This appetite suppression typically begins within days and increases as your dose escalates from 2.5 mg up to the maximum 15 mg.
What this means for your diet:
- Portion sizes naturally decrease — you may eat only 50–60% of your usual meals
- Fatty or heavy foods often become unappealing
- Thirst may increase — stay hydrated with water
- Some foods trigger nausea or indigestion more than others
- Eating speed matters — slow eating prevents discomfort
The appetite suppression is not permanent; it gradually reduces over time as your body adjusts to the medication. Your dose may need adjusting if appetite returns significantly.
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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.
Practical Nutrition Tips While On Mounjaro
Eat nutrient-dense foods: Because portions are smaller, focus on meals rich in protein, fibre, and micronutrients. Lean proteins (chicken, fish, eggs) should form the base of each meal. Include plenty of vegetables, whole grains, and healthy fats from sources like olive oil and avocado.
Avoid triggers: Ultra-processed foods, high-fat takeaways, and sugary items often cause nausea or stomach discomfort on Mounjaro. Fatty fried foods are particularly common triggers. Alcohol may also worsen side effects — discuss this with your GP.
Hydration and electrolytes: Increased thirst and possible nausea mean staying hydrated is critical. Aim for 6–8 glasses of water daily. If you experience significant nausea or vomiting, consider consulting your prescriber about electrolyte balance.
Track your food and weight progress using our free progress tracker to identify which foods work best for your body on Mounjaro.
- 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 on Mounjaro to lose weight most effectively?
Focus on high-protein, low-fat meals with plenty of vegetables and whole grains. Lean proteins (fish, chicken, eggs, legumes) should form the base of every meal because protein keeps you satisfied longer with smaller portions. Avoid fried, fatty, and ultra-processed foods — these trigger nausea and discomfort more often on Mounjaro. Your body will naturally eat less due to the medication, so quality of food matters more than quantity.
Can I eat normally while taking Mounjaro?
Not immediately. Most people find eating their normal portion sizes physically uncomfortable within the first week of Mounjaro. Portions naturally reduce to 40–60% of your usual intake due to increased satiety. Some people report lasting appetite suppression; others find it gradually reduces over weeks or months. Your GP can advise on adjusting your dose if appetite returns significantly.
Is a low-calorie diet needed if I'm on Mounjaro?
No — most people create a natural calorie deficit through reduced portions alone, as appetite suppression is the medication's primary mechanism. Extremely low-calorie diets (under 800 kcal daily) are not recommended without medical supervision. The NHS recommends losing 0.5–1 kg per week through a balanced diet and activity; Mounjaro supports this by reducing hunger rather than requiring severe restriction.
What foods should I avoid on Mounjaro?
Fatty, greasy, and fried foods are the most common triggers for nausea and stomach discomfort. High-sugar foods, very hot foods, and alcohol may also cause problems. Keep a food diary during your first few weeks to identify your personal triggers — everyone responds differently. If certain foods consistently cause side effects, avoid them and substitute nutrient-dense alternatives your body tolerates well.
Do I need to count calories or follow a specific diet plan on Mounjaro?
Formal calorie counting is optional — most people achieve weight loss through portion control alone thanks to the medication's appetite-suppressing effects. However, some find tracking food helps identify triggers and ensures balanced nutrition. Your GP or a registered dietitian can provide personalised guidance. Use our GLP-1 weight loss calculator alongside a food diary to monitor your progress throughout your Mounjaro treatment.
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.