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), your appetite naturally decreases, which means you're eating smaller portions. This makes it essential to prioritise nutrient-dense foods—especially protein—to maintain muscle mass and support your health during weight loss. Protein intake on Mounjaro depends on your body weight, activity level, and personal health goals, but most adults should aim for a specific daily target to prevent muscle loss whilst losing fat.
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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.
Protein Recommendations On Mounjaro
The standard recommendation for protein intake is 0.8 grams per kilogram of body weight for sedentary adults, but on Mounjaro, many nutrition experts recommend 1.2 to 1.6 grams per kg to preserve lean muscle mass during weight loss. This means:
- A 70 kg adult should aim for approximately 84–112 grams of protein daily
- An 80 kg adult should aim for 96–128 grams daily
- An 90 kg adult should aim for 108–144 grams daily
Higher protein intake becomes especially important because Mounjaro reduces appetite significantly—you're eating less overall, so each meal must contain quality nutrients. Without adequate protein, your body may break down muscle tissue alongside fat during weight loss, which slows metabolism and affects body composition. Your GP or a registered dietitian can assess your individual needs based on your current weight, activity level, and any existing health conditions.
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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.
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Practical Protein Strategies On Mounjaro
Because Mounjaro causes reduced appetite and sometimes nausea in the early weeks, aim to distribute protein evenly across meals rather than loading one meal with large portions. Include protein-rich foods at every eating occasion: lean meats, fish, eggs, Greek yoghurt, cottage cheese, legumes, and nuts. If appetite is very low, consider a high-protein drink or powder to reach daily targets without feeling overfull. Stay hydrated and eat slowly—Mounjaro slows gastric emptying, so smaller meals digested slowly feel more satisfying. Track your protein intake using a food diary or app initially; this helps you understand whether you're meeting targets without forcing yourself to eat uncomfortably large amounts.
- 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 lose muscle on Mounjaro if I don't eat enough protein?
Yes. Without adequate protein (1.2–1.6 g/kg body weight), your body can break down muscle tissue alongside fat during weight loss, even on Mounjaro. This slows metabolism and affects body composition. Prioritising protein helps preserve lean mass whilst losing weight effectively.
Is 0.8g per kg enough protein on Mounjaro?
The standard 0.8 g/kg is the minimum for sedentary adults but is likely insufficient during active weight loss on Mounjaro. Most experts recommend 1.2–1.6 g/kg instead to protect muscle. Your GP or dietitian can personalise this based on your activity level and health goals.
What if I struggle to eat enough protein due to nausea on Mounjaro?
Distribute protein across smaller meals rather than eating large portions at once. High-protein drinks, Greek yoghurt, eggs, and fish are easier to digest. Start with lower tirzepatide doses and build up gradually—appetite tolerance typically improves. Inform your prescriber if nausea persists beyond week 4.
How does protein intake relate to weight loss on Mounjaro?
Adequate protein supports sustainable weight loss by preserving muscle mass, maintaining metabolic rate, and increasing satiety. Mounjaro reduces appetite, so each meal must be nutrient-dense. Protein also helps stabilise blood sugar and supports the medication's appetite-reduction mechanism.
Should I count protein differently if I'm very overweight?
For very obese individuals, some experts recommend using "adjusted body weight" rather than actual weight for protein calculation—your GP or registered dietitian can advise. The goal is to preserve muscle whilst losing fat, not to under-eat due to high current weight. Personal assessment is important.
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