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 Powder for Weight Loss — And UK Prescription Options
Protein whey powder is often used as part of a weight management strategy in the UK, as it can help you feel fuller for longer and preserve muscle during weight loss. However, if you're looking for additional support, prescription weight loss medication is available to eligible adults. This guide explains how protein fits into weight management, and what prescription options are available through the NHS and privately in the UK.
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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.
UK-Licensed Prescription Weight Loss Medications
If you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions, you may be eligible for prescription weight loss medication in the UK. Three main options are currently licensed:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed average weight loss of 15–21% body weight alongside a reduced-calorie diet.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. Evidence suggests average weight loss of around 15% body weight.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, injected daily. Another established option for weight management.
All three are prescription-only medicines and require a clinical assessment before being prescribed. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses if you're considering these options.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
NHS vs Private Access — How to Find Out If You're Eligible
NHS access: Weight loss medications are available through specialist tier 3 weight management services. Ask your GP for a referral to your local service. Availability and waiting times vary significantly by region (ICB).
Private access: You can also access prescription weight loss treatment privately through a UK-licensed prescriber following an online clinical assessment, without needing an NHS referral. Costs typically range from £130–£320 per month depending on the medication and dose.
Whether you choose protein supplementation, lifestyle changes, medication, or a combination, start a conversation with your GP about what's right for your personal health situation. Use our free BMI calculator to check your starting point, and our progress tracker to monitor your weight management journey over time.
- 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 protein powder alone help me lose weight?
Protein powder can be a useful tool alongside a calorie deficit and regular physical activity. High-protein diets may help preserve muscle mass during weight loss and support satiety. However, sustainable weight loss requires an overall reduced-calorie diet. If you're struggling with weight management despite dietary changes, prescription medication may be worth discussing with your GP.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) works on two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) works on GLP-1 alone. Clinical trials showed Mounjaro may produce slightly higher average weight loss, though individual results vary significantly. Both are once-weekly injections. Your prescriber will assess which is more appropriate for you.
Am I eligible for prescription weight loss medication on the NHS?
Generally, you may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults have lower thresholds (BMI 27.5+). Ask your GP for a referral to specialist weight management services in your area.
How quickly will I lose weight with prescription medication?
Weight loss varies between individuals, but clinical trials typically show noticeable results within 12–16 weeks. The NHS recommends losing 0.5–1 kg per week for sustainable outcomes. Prescription medications work best alongside dietary changes and increased physical activity, not instead of them.
Can I use protein powder while taking Mounjaro or Wegovy?
Yes, many people combine protein supplementation with weight loss medication. In fact, adequate protein intake is especially important during weight loss to help preserve muscle mass. Always mention any supplements to your prescriber during your clinical assessment to ensure there are no interactions with your medication.
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.