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's the Best Diet to Use With Mounjaro?
When taking Mounjaro (tirzepatide), your diet plays a crucial role in supporting weight loss alongside the medication. While Mounjaro helps reduce appetite and food cravings, the most effective results come from combining it with a healthy, reduced-calorie diet. This guide covers NHS-aligned nutrition strategies, practical meal planning tips, and what to eat (and avoid) while on Mounjaro treatment in the UK. A balanced approach—not restriction—works best with this medication.
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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 Diet Works Alongside Mounjaro Treatment
Mounjaro works by activating GLP-1 and GIP receptors, which help regulate appetite and blood sugar. However, the medication alone does not clinically studied weight loss—it works most effectively when combined with dietary changes and increased physical activity. NHS guidance recommends a reduced-calorie diet creating roughly a 500 kcal daily deficit, which typically supports a loss of 0.5–1 kg per week.
Clinical trials showed participants on Mounjaro achieved best results when they also followed structured eating patterns. Your diet should focus on:
- Protein at each meal — supports satiety and preserves muscle during weight loss
- Whole foods — vegetables, fruits, lean proteins, whole grains
- Hydration — many people mistake thirst for hunger, especially on Mounjaro
- Small, frequent meals — Mounjaro slows gastric emptying, so smaller portions feel more satisfying
Because Mounjaro reduces appetite, you may find eating requires conscious effort initially. The medication's effect is most noticeable in the first 4–8 weeks, so establishing good eating habits early supports long-term success.
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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
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Best Foods and Eating Patterns on Mounjaro
Protein-rich foods are essential—they keep you fuller longer and support muscle retention during weight loss. Include lean meats, fish, eggs, Greek yoghurt, legumes, and tofu. Vegetables provide volume and nutrients with minimal calories; aim for variety and colour.
Many people on Mounjaro report nausea or reduced appetite, particularly in the first weeks. If this occurs, eat small, frequent meals rather than forcing large portions. Avoid high-fat, greasy foods, which can worsen nausea, and limit simple sugars and refined carbohydrates.
Track your intake using our free BMI calculator and progress tracker to monitor both weight and how you're feeling. Some people benefit from keeping a food diary to identify patterns. Remember: Mounjaro works best when combined with sustainable lifestyle changes, not extreme restriction. Your GP or dietitian can provide personalised guidance based on your health.
- 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 on Mounjaro?
Not exactly—most people eat less because Mounjaro reduces appetite. Rather than eating "normally", focus on eating nutritious foods in smaller portions. The medication helps you feel satisfied with less food, which supports weight loss alongside a reduced-calorie diet. Listen to hunger and fullness cues, and eat when genuinely hungry.
What if I feel sick or can't eat enough on Mounjaro?
Nausea is common, especially in the first 4 weeks. Eat smaller, more frequent meals; avoid greasy or heavy foods; stay hydrated; and eat slowly. If nausea persists, contact your GP or the prescriber who issued your Mounjaro kwikpen. Dose adjustments or timing changes may help. Severe or persistent side effects require medical review.
Should I follow a specific diet like keto or low-carb on Mounjaro?
NHS guidance supports a balanced, reduced-calorie diet rather than extreme restriction. While low-carb approaches can work, they're not necessary with Mounjaro. A Mediterranean-style diet with whole foods, lean proteins, vegetables, and healthy fats is evidence-based and sustainable. Work with your GP or a registered dietitian for a plan suited to your health.
How does Mounjaro dose titration affect my diet?
As your Mounjaro dose increases (from 2.5 mg up to 15 mg), appetite suppression typically becomes stronger. You may need to adjust portion sizes and meal frequency as you progress. Starting with good eating habits at lower doses helps you adapt smoothly to higher doses and their stronger effects on appetite.
Is there a difference between diet on Mounjaro versus Wegovy?
Both Mounjaro and Wegovy reduce appetite through similar mechanisms, so basic dietary principles are the same: balanced, reduced-calorie eating with adequate protein. However, Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist while Wegovy is GLP-1 only, so individual responses vary. Your prescriber can advise on the best diet approach for your specific medication.
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.