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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How Much Protein Do I Need on Mounjaro?
When taking Mounjaro (tirzepatide) for weight management, protein intake becomes more important than before—especially because the medication reduces appetite, making it easier to accidentally under-eat. Most UK clinical guidance suggests aiming for 0.8–1.0g of protein per kilogramme of body weight daily whilst on Mounjaro, with emphasis on maintaining muscle mass during weight loss. Your GP or prescriber can give personalised advice based on your individual health, activity level, and weight loss goals.
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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.
Mounjaro vs Wegovy: Protein Needs and Mechanism Differences
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 receptor agonist medications licensed in the UK for weight management, but they work slightly differently—and this affects nutritional needs. Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy activates only the GLP-1 pathway. Clinical trial data shows that SURMOUNT (Mounjaro's trial) and STEP (Wegovy's trial) both achieved significant weight loss when combined with a reduced-calorie diet and increased physical activity. Because both medications suppress appetite, the risk of under-eating protein is similar on either medication. General guidance suggests 1.2–1.6g protein per kilogramme of body weight for those actively exercising, or at minimum 0.8g/kg for sedentary individuals. Try our GLP-1 weight loss calculator to understand potential weight loss at different doses—knowing your projected goal weight helps calculate your protein target.
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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 Strategy on Mounjaro and Wegovy
The key challenge on both medications is eating enough protein despite reduced appetite. Strategies include: consuming protein at every meal (eggs, Greek yoghurt, lean meat, fish, pulses), choosing protein-rich foods that are easier to stomach (smoothies, soups, soft proteins), and spacing protein throughout the day rather than attempting large meals. Because Mounjaro and Wegovy slow gastric emptying (stomach emptying), larger protein meals may feel uncomfortable—smaller, frequent meals work better. A typical target on Mounjaro UK prescription is 80–120g protein daily for a 70kg person, though your prescriber may adjust based on your activity and weight loss rate. If you experience persistent nausea that prevents eating enough protein, always inform your GP or prescriber—they may adjust your dose or provide additional support.
- 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's the difference between Mounjaro and Wegovy protein needs?
Both medications suppress appetite similarly, so protein requirements are comparable: roughly 0.8–1.6g per kg body weight depending on activity level. The main difference is mechanism—Mounjaro is a dual GIP+GLP-1 agonist whilst Wegovy is GLP-1 only. This affects weight loss speed but not protein requirements significantly. Your prescriber will tailor guidance to your individual needs.
Can I get enough protein if Mounjaro reduces my appetite?
Yes, but it requires planning. Choose protein-rich foods that are easier to tolerate (Greek yoghurt, smoothies, fish, eggs), eat smaller meals more frequently, and spread protein intake throughout the day. If nausea prevents adequate protein intake, speak to your GP—dose adjustment or anti-nausea support may help.
How do I calculate my protein target on Mounjaro?
A simple approach: multiply your body weight in kilograms by 0.8 to 1.6, depending on activity level. For example, a 70kg person would aim for 56–112g protein daily. Use our free weight converter to check your weight in kg if needed, then discuss your personal target with your prescriber.
Is high protein intake on Mounjaro safe?
Yes, protein intake of 1.2–2.0g per kg body weight is safe for most adults. However, if you have kidney disease, discuss protein targets with your GP first. High protein supports muscle preservation during weight loss, which is beneficial on Mounjaro.
Why is protein more important on Mounjaro than before?
Because appetite suppression makes it easy to under-eat—including not consuming enough protein. Insufficient protein during weight loss increases muscle loss risk. Prioritising protein helps preserve lean muscle mass as you lose weight, which supports metabolism and longer-term weight management success.
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.