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, Protein Shakes, and Weight Loss in the UK
When taking Mounjaro (tirzepatide) for weight management in the UK, protein shakes are often recommended as part of a reduced-calorie diet. This guide explains how protein-based nutrition supports weight loss alongside Mounjaro, compares this approach with Wegovy (semaglutide), and covers UK eligibility, dosing, and practical considerations. Protein shakes help maintain muscle mass during weight loss and can reduce appetite alongside the medication's natural effects. Use our free GLP-1 weight loss calculator to estimate potential outcomes with Mounjaro at different doses.
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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.
How Mounjaro and Protein Shakes Work Together for Weight Loss
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—a prescription-only injection licensed in the UK for weight management. It activates two hormone pathways that help regulate appetite, reduce food cravings, and slow gastric emptying. Protein shakes complement this mechanism by providing sustained satiety and supporting muscle preservation during calorie deficit.
Clinical trials (SURMOUNT-1) showed Mounjaro users lost an average of 15–21% body weight over 72 weeks when combined with dietary changes and increased physical activity. Individual results vary significantly. Protein intake during weight loss is important: the NHS and nutritionists recommend approximately 1.2–2g of protein per kg of body weight daily to preserve lean muscle mass, especially when taking weight loss medications.
- Mounjaro doses range from 2.5 mg to 15 mg once weekly
- Starting dose is 2.5 mg, increasing every 4 weeks if tolerated
- Protein shakes should be part of a structured, reduced-calorie diet plan
- Both medication and nutrition changes are needed for sustainable results
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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.
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Mounjaro vs Wegovy: Mechanism, Trials, and Suitability
Wegovy (semaglutide) is a GLP-1 receptor agonist only—it activates a single hormone pathway, whereas Mounjaro activates both GIP and GLP-1. STEP trial data showed Wegovy users lost approximately 14.9% body weight at 68 weeks on the maximum 2.4 mg dose. Mounjaro's dual mechanism may offer slightly higher average weight loss (15–21%), though individual responses vary considerably and direct comparison depends on individual health factors.
Both medications are prescription-only in the UK and require clinical assessment. A licensed prescriber will evaluate your eligibility based on BMI and weight-related health conditions. Both work best with protein-rich nutrition, reduced calories, and increased physical activity. Neither medication is "better"—suitability depends on individual health profile, tolerability, and prescriber recommendation. Your GP or private prescriber can assess which is appropriate for you following a clinical assessment.
- 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 use protein shakes whilst taking Mounjaro?
Yes. Protein shakes are often recommended during Mounjaro treatment to maintain muscle mass during weight loss and support satiety. Choose shakes with minimal added sugar and aim for 20–30g protein per serving. Always combine with a structured, reduced-calorie diet plan and consult your prescriber about your nutritional strategy.
How much protein should I eat daily on Mounjaro?
The NHS recommends approximately 1.2–2g of protein per kg of body weight daily during weight loss medication treatment. Use our free GLP-1 weight loss calculator above to estimate your current weight, then multiply by this range. A nutritionist or dietitian can personalise this for you.
Is Mounjaro better than Wegovy for weight loss?
Both are licensed for weight management in the UK. Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist; Wegovy (semaglutide) is GLP-1 only. Clinical trials show Mounjaro average weight loss of 15–21% and Wegovy approximately 14.9%, but individual results vary. A prescriber will assess which is suitable for your health profile.
How long does it take to see results with Mounjaro and protein shakes?
Most people notice appetite reduction within 1–2 weeks of Mounjaro. Measurable weight loss typically becomes apparent within 4–8 weeks when combined with a reduced-calorie diet and protein intake. Results are gradual and sustainable—the UK recommends losing no more than 0.5–1 kg per week.
Do I need NHS approval to get Mounjaro in the UK?
Mounjaro is available through NHS specialist tier 3 weight management services (requires referral from your GP) or through private online prescribing following clinical assessment. NHS access varies by region and availability. Private prescribers can issue prescriptions if you're clinically eligible without a formal NHS referral.
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.