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 Meal Plans and Prescription Medication in the UK
Meal plan delivery services can support weight loss, but many people also benefit from prescription weight management options available in the UK. If you're looking to lose weight, combining a structured meal plan with eligible medical support may offer better results. This guide covers UK-licensed prescription options, eligibility criteria, and how to discuss these choices 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 Prescription Weight Management Options
Three prescription medications are licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 or GIP/GLP-1 receptor agonist injections that may help reduce appetite and support weight loss alongside dietary changes.
In clinical trials, Mounjaro helped participants lose an average of 15–21% of their body weight over 72 weeks. Wegovy showed similar results, with participants losing approximately 14.9% on average. Both are once-weekly injections requiring a prescription. Saxenda is a daily injection with slightly lower average weight loss outcomes.
- All three are prescription-only medicines
- Eligibility depends on BMI and health conditions
- Available via NHS specialist services or private prescription
- Results vary significantly between individuals
- Used alongside reduced-calorie diet and physical activity
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 Access and Private Options in the UK
NHS access is through tier 3 specialist weight management services — your GP can refer you, though availability varies by region and waiting lists can be lengthy. Private access is available through GPhC-registered online prescribers following a clinical assessment, with no NHS referral required.
To find out if you're eligible, use our free BMI calculator to check your current BMI. Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes or high blood pressure, may qualify. Your GP or a licensed prescriber will assess your individual suitability. Combining prescription support with a structured meal plan can enhance results for eligible adults.
- 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.
What is the difference between meal plans and prescription weight loss medication?
Meal plan delivery services provide structured eating guidance, while prescription medications like Mounjaro and Wegovy work by reducing appetite and cravings. The most effective approach for eligible adults combines both — a managed diet plan alongside medical support if clinically appropriate.
Can I get prescription weight loss medication on the NHS?
Yes, if you meet eligibility criteria. You'll need referral to a tier 3 specialist weight management service through your GP. Availability varies significantly by region. Private options are also available without NHS referral, assessed by a licensed prescriber.
How much weight can I expect to lose with medication?
Clinical trials showed average losses of 15–21% body weight with Mounjaro and approximately 15% with Wegovy over several months. However, individual results vary significantly. Your personal outcome depends on adherence, diet, activity level, and individual metabolism.
Is prescription weight loss medication safe?
All UK-licensed medications undergo rigorous safety testing. Side effects are common initially (nausea, diarrhoea) but often improve. Always discuss medical history with your prescriber — some people cannot take these medications due to contraindications.
How do I know if I'm eligible for prescription weight loss treatment?
Use our free BMI calculator to check your BMI. Adults with BMI 30+ or BMI 27+ with weight-related health conditions may be eligible. Your GP or a licensed prescriber will assess your individual circumstances and medical history.
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.