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
Protein Shakes For Meal Replacement And Weight Loss
Protein shakes can support weight loss when used as part of a structured plan, but they work best alongside dietary changes and increased physical activity. Replacing one meal per day with a protein shake may help create a calorie deficit, which is essential for sustainable weight loss. However, shakes alone are not a weight loss solution — they're a tool that works alongside other lifestyle changes. Our free BMI calculator and GLP-1 weight loss calculator can help you understand your starting point and explore different weight management approaches suited to your situation.
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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 Protein Shakes Support Weight Loss
Protein shakes help with weight loss through several mechanisms:
- Calorie control: A typical meal replacement shake contains 150–250 kcal, significantly less than most meals. The NHS recommends a calorie deficit of around 500 kcal per day for sustainable weight loss of 0.5–1 kg per week. One shake per day contributes to this deficit.
- Increased satiety: Protein is the most satiating macronutrient — it helps you feel fuller for longer, reducing cravings and snacking between meals.
- Preservation of muscle: During weight loss, adequate protein intake helps preserve lean muscle mass, which is important for metabolism and body composition.
- Convenience: For busy people, a shake is quick and requires no preparation, making it easier to stick to a weight management UK plan.
However, shakes are most effective when combined with a reduced-calorie diet and increased physical activity — not as a replacement for these lifestyle changes.
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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.
Protein Shakes vs. Prescription Weight Loss Medication
Protein shakes and prescription weight loss medications like GLP-1 injections (Mounjaro and Wegovy) work differently. Shakes provide protein and calorie control; GLP-1 medications suppress appetite at a hormonal level and may help you feel satisfied with smaller portions. Many people use both together — a shake for convenience and structured calorie intake, combined with medication prescribed by their GP following clinical assessment. For weight loss injections uk eligibility, you'll need a BMI of 30 or above, or 27 or above with weight-related health conditions. Use our GLP-1 weight loss calculator to explore potential outcomes with medication, and try our progress tracker to log your weight loss journey alongside any dietary changes.
- 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.
Are meal replacement shakes effective for weight loss?
Meal replacement shakes can help with weight loss when used to create a calorie deficit alongside dietary changes and physical activity. One shake per day may save 500–800 kcal compared to a typical meal. However, shakes alone are not sufficient — sustainable weight loss requires overall lifestyle changes, not just replacing meals.
Can I use protein shakes with Mounjaro or Wegovy?
Yes. Many people combine protein shakes with GLP-1 medications for weight management. Shakes provide convenient, controlled calories and protein, while the medication helps suppress appetite. Always discuss your complete diet plan with your prescriber to ensure it works alongside your medication safely.
How many protein shakes can I have per day?
Most NHS guidance suggests replacing no more than one meal per day with a shake. Replacing multiple meals can lead to nutritional deficiencies and is typically only recommended under medical supervision (e.g., very low calorie diet programmes). Balance shakes with whole foods to ensure adequate nutrition.
What should I look for in a meal replacement shake?
Choose shakes with at least 15–20g protein, below 250 kcal per serving, and ideally containing fibre, vitamins, and minerals. Avoid shakes high in added sugar. Read the nutrition label carefully. Your GP or a registered dietitian can recommend specific products suited to your health needs.
How does a protein shake compare to NHS weight loss guidance?
The NHS Weight Loss Plan recommends a balanced reduced-calorie diet (around 1200–1500 kcal per day) alongside physical activity. Protein shakes can fit into this plan as one meal replacement, but should be part of a broader dietary approach that includes whole foods, vegetables, and fruits for balanced nutrition.
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.