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
How Much Protein Should You Eat On Mounjaro?
When taking Mounjaro (tirzepatide), protein intake becomes even more important to help preserve muscle mass during weight loss. While there is no single NHS-approved "Mounjaro protein requirement", evidence suggests aiming for 1.2 to 1.6 grams of protein per kilogram of body weight daily is beneficial. This ensures your body prioritises fat loss over muscle loss as you lose weight. Your GP or registered dietitian can personalise this recommendation based on your individual health, activity level, and weight loss goals. Alongside balanced nutrition, using our GLP-1 weight loss calculator can help you project realistic outcomes with tirzepatide.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Why Protein Matters When Taking Mounjaro
Mounjaro is a dual GIP and GLP-1 receptor agonist that significantly reduces appetite and food intake. Whilst this helps create the calorie deficit needed for weight loss, it also increases the risk of losing muscle alongside fat if protein intake is too low. Muscle tissue is metabolically active—losing it slows your metabolism and makes maintaining weight loss harder long-term.
General protein guidelines when taking Mounjaro:
- Minimum: 1.2g protein per kg body weight daily (e.g., a person weighing 80kg should aim for at least 96g daily)
- Optimal for weight loss: 1.4–1.6g per kg daily to maximise muscle preservation
- Higher activity: If you exercise regularly, aim toward the upper range (1.5–1.6g/kg)
Spreading protein across meals—rather than concentrated in one meal—may also support satiety and muscle protein synthesis more effectively. Your prescriber can provide personalised advice based on your Mounjaro dose titration schedule and individual circumstances.
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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 Protein Sources and NHS Context
Good UK protein sources on a Mounjaro-friendly diet include lean chicken breast, fish (especially omega-3 rich varieties like salmon), eggs, Greek yoghurt, cottage cheese, beans, lentils, and tofu. Many people find smaller, protein-rich meals work better on Mounjaro because the medication slows gastric emptying and increases fullness signals.
The NHS does not publish specific protein targets for Mounjaro users, but NICE guidance emphasises that weight management should include adequate protein to prevent muscle loss. If you're unsure about your individual protein needs, ask for a referral to a registered dietitian through the NHS, or discuss personalised nutrition with your prescriber. Track your progress using our free progress tracker to monitor both weight and how you feel on your current intake.
- 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.
How much protein per day on Mounjaro?
Most evidence suggests 1.2–1.6g per kilogram of body weight daily. For an 80kg person, that's 96–128g daily. Spread across three to four meals for best results. Your GP or dietitian can personalise this based on your activity level and health.
Can you lose muscle on Mounjaro if protein is too low?
Yes. Mounjaro suppresses appetite significantly, making it easy to under-eat. Without adequate protein, your body may break down muscle tissue alongside fat. This is why protein remains crucial even though you're eating less overall.
Is there NHS guidance on Mounjaro nutrition?
The NHS does not publish specific Mounjaro nutrition protocols, but NICE guidance emphasises preserving lean body mass during weight loss. If prescribed via NHS tier 3 services, you may be offered dietitian support. Private prescribers should also discuss nutrition with you.
What are the best protein sources on Mounjaro?
Lean meats, fish, eggs, Greek yoghurt, cottage cheese, beans, lentils, and tofu all work well. Because Mounjaro slows digestion, smaller, protein-rich meals often feel more manageable than large portions.
Should I take protein supplements with Mounjaro?
Supplements are optional if you can meet your target through food. However, a high-protein shake can be convenient on days when appetite is very suppressed. Always choose a quality product and discuss with your prescriber or dietitian if unsure.
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.