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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Mounjaro and Meals — What You Need to Know
Mounjaro (tirzepatide) is a prescription-only weight management injection that affects how your body responds to food and hunger. Many people taking Mounjaro find their appetite naturally decreases, which means meal planning and food choices need to change. Understanding how Mounjaro works with meals, what to eat when experiencing side effects, and how to maintain proper nutrition is essential for successful, sustainable weight management alongside reduced-calorie eating and increased physical activity.
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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.
How Mounjaro Affects Your Appetite and Eating
Mounjaro works as a dual GIP and GLP-1 receptor agonist—activating two natural hormone pathways that help regulate appetite and fullness signals. Many people report feeling satisfied after eating significantly smaller portions than before, sometimes after just a few mouthfuls. This reduced appetite is why meal planning becomes important: you may eat less without realising it, risking inadequate nutrition if you don't choose nutrient-dense foods.
The strength of appetite reduction varies between individuals and often increases as your dose titration progresses. Starting on a lower Mounjaro KwikPen dose (2.5 mg) may have a mild effect, while higher doses (10 mg, 15 mg) typically produce stronger appetite suppression. Some people also experience slower gastric emptying—food moves through your stomach more slowly—which creates prolonged fullness and can affect meal timing and portion sizes.
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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.
Nutrition, Meal Planning, and Side Effects
Because Mounjaro reduces hunger significantly, eating enough protein, vegetables, and micronutrient-rich foods becomes critical. Small portions of nutrient-dense meals are better than larger volumes of empty-calorie foods. Nausea and diarrhoea are common Mounjaro side effects—particularly when starting or after dose increases—so eating smaller, more frequent meals may help.
Staying hydrated is essential, especially if experiencing diarrhoea. Include foods rich in iron, B vitamins, and calcium to prevent deficiency during weight loss. Consider consulting your GP or a registered dietitian for personalised nutrition guidance while on tirzepatide treatment. Our GLP-1 weight loss calculator can help you estimate results, but your healthcare team should monitor your overall health and nutritional status throughout your treatment.
- 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.
Will I feel hungry on Mounjaro?
Most people experience significantly reduced hunger on Mounjaro, especially at higher doses. Appetite suppression is a key mechanism of action for tirzepatide. However, individual experiences vary—some people notice mild appetite reduction while others feel almost no hunger. This is why portion sizes often naturally decrease without conscious restriction.
What should I eat while taking Mounjaro?
Focus on protein-rich foods (chicken, fish, eggs, beans), plenty of vegetables, whole grains, and healthy fats. Small portions of nutrient-dense meals are better than larger volumes. Avoid highly processed foods and sugary drinks. If experiencing nausea or diarrhoea, eat smaller meals more frequently and stay hydrated.
Can I eat normally while on Mounjaro?
Many people find "normal" portions feel uncomfortably large while on Mounjaro. Your appetite naturally adapts to smaller portions. Eating "normally" may cause overfullness, nausea, or discomfort. Instead, listen to your body's signals and eat when genuinely hungry, focusing on nutrient-dense foods to ensure adequate nutrition.
How does Mounjaro dose affect appetite?
Appetite suppression typically increases as your Mounjaro dose titration progresses. Starting dose (2.5 mg) may have mild effects, while maintenance doses (10–15 mg) usually produce stronger appetite reduction. Most people reach their target effect within 4–8 weeks on their maintenance dose.
Should I see a dietitian while taking Mounjaro?
Consulting a registered dietitian is recommended, especially if you're experiencing side effects or struggling with nutrition. Your GP can also provide guidance. A dietitian can ensure your reduced calorie intake still meets your nutritional needs and help you develop sustainable eating habits that work with Mounjaro's effects.
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.