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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Weight Loss Prep Kitchen: UK Prescription Medication Options
The weight loss prep kitchen concept focuses on food preparation, but for many UK adults looking to lose weight, prescription medication can be a valuable tool alongside dietary changes. If you have a BMI of 30 or above, or 27 or above with weight-related health conditions, you may be eligible for prescription weight loss medication through the NHS or private prescribers. This guide covers the UK-licensed options available, how to find out if you qualify, and the next steps to discuss with your GP.
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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
Three prescription-only medications are currently licensed in the UK for weight management in adults. Mounjaro (tirzepatide) is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist — in clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. Wegovy (semaglutide) is another once-weekly injection that acts as a GLP-1 agonist, with clinical trial data showing average weight loss of around 15% of body weight. Saxenda (liraglutide) is a daily injection, also a GLP-1 agonist, offering an alternative for those who prefer daily dosing.
All three are prescription-only and require a clinical assessment before being prescribed. Eligibility depends on your BMI, any weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), and your overall health profile. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher cardiovascular risk at lower weights. Use our free BMI calculator to check your starting point, and our GLP-1 weight loss calculator to explore potential 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 in the UK
NHS access: Weight loss medications are available through specialist tier 3 and tier 4 weight management services. You'll typically need a GP referral, and availability varies significantly by region. Waiting lists can be lengthy — in some areas, several months to over a year. Once approved, medication is usually free on the NHS.
Private access: You can obtain a prescription through a GPhC-registered online pharmacy following an online clinical assessment with a UK-licensed prescriber. This route doesn't require an NHS referral and can be faster, though you'll pay privately (typically £129–£320 per month depending on dose). Either way, the medication and clinical support are the same — the difference is in the pathway and cost. Speak to your GP first; they can advise on NHS waiting times and whether private treatment might suit you.
The most important step is having an honest conversation with your GP about your weight and health goals. Ask about NHS weight management services in your area, current waiting times, and whether you might be eligible. Your GP can assess your overall health, any medications you're taking, and discuss whether prescription weight loss medication is appropriate for you. Prescription medications work best alongside lifestyle changes — including the kind of dietary planning that the "prep kitchen" concept emphasises. Track your progress with our free progress tracker to monitor both your weight loss journey and how dietary and medication changes affect your health 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.
Am I eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. For some ethnic groups, lower BMI thresholds apply. Your GP or a licensed prescriber can assess your eligibility after reviewing your medical history.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist with average weight loss of 15–21%, while Wegovy is a GLP-1 agonist only with average weight loss around 15%. Mounjaro uses once-weekly doses up to 15 mg, while Wegovy goes up to 2.4 mg weekly. Both require prescription and clinical assessment, and individual results vary.
How long does it take to access weight loss medication on the NHS?
Waiting times vary significantly by region. Some areas offer assessment within weeks, while others have waiting lists of several months to over a year. Ask your GP about current waiting times for your local NHS weight management service. Private prescribing is typically faster.
Can I use weight loss medication without changing my diet?
Prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. These medications support appetite reduction and fullness, but they're not a substitute for lifestyle changes. Combining medication with dietary planning and exercise produces the best long-term results.
Do I need to stay on weight loss medication forever?
Your prescriber will discuss this with you. Some people use it short-term to achieve weight loss, then transition to maintenance through lifestyle alone. Others continue longer-term. This depends on your health goals, weight loss achieved, and how your body responds. Your GP or prescriber will tailor the approach to your situation.
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.