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 Diet and Weight Loss: UK Medication Options
A high-protein diet can support weight loss by helping you feel fuller for longer and preserving muscle mass during calorie reduction. However, diet alone isn't always enough for everyone. If you're struggling to lose weight through dietary changes, prescription weight management medications are available in the UK for eligible adults. This guide explains how protein fits into a weight loss strategy and outlines the prescription options your GP can discuss with you.
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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 Weight Loss Medications for Eligible Adults
If you have a BMI of 30 or above (or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure), 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, once-weekly injection. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, once-weekly injection. Average weight loss was approximately 15% in clinical trials.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, once-daily injection, a longer-established option.
These medications work alongside a reduced-calorie diet and increased physical activity — they are not replacements for lifestyle changes. Use our free GLP-1 weight loss calculator to explore potential weight loss outcomes at different doses.
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 and How to Find Out If You're Eligible
NHS access: Weight loss medications are available through NHS specialist weight management services (tier 3/4), but you'll need a referral from your GP. Availability varies significantly by region and waiting times can be lengthy. Your GP can assess whether you meet local criteria and refer you if appropriate.
Private access: You can access prescription weight loss medication through a GPhC-registered online prescriber without an NHS referral, though this involves a cost. Either way, a licensed prescriber must assess your health before prescribing. Check your BMI using our free BMI calculator to see where you fall, then discuss weight management options with your GP.
- 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 get weight loss medication on the NHS?
Yes, if you meet eligibility criteria (BMI ≥30 or ≥27 with weight-related health conditions), you can be referred to NHS specialist weight management services. However, availability and waiting times vary significantly by region. Ask your GP about tier 3 services in your area.
How does protein help with weight loss?
Protein increases satiety, helping you feel fuller for longer and reducing overall calorie intake. It also supports muscle preservation during weight loss and has a higher thermic effect than other macronutrients. A protein-rich diet is most effective when combined with a calorie deficit.
What's the difference between Mounjaro and Wegovy?
Mounjaro uses dual GIP+GLP-1 action and showed 15–21% average weight loss. Wegovy uses GLP-1 alone and showed approximately 15% average weight loss in trials. Both are once-weekly injections. Individual results vary; your prescriber can advise which is more suitable.
Do I need to follow a strict diet if I take weight loss medication?
Yes, prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They are not standalone treatments. They help reduce appetite and cravings, making it easier to maintain a healthy diet, but lifestyle changes remain essential.
What BMI qualifies me for prescription weight loss treatment in the UK?
Adults with a BMI of 30 or above are eligible. Those with a BMI of 27–29.9 may also qualify if they have weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our BMI calculator to check yours and discuss eligibility with your GP.
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.