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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Best Weight Loss Program For You — UK Medication & Lifestyle Options
Finding the best weight loss program for your needs depends on your health, BMI, and personal circumstances. In the UK, you have access to NHS weight management services, prescription weight loss medications (like Mounjaro and Wegovy), and lifestyle-based programmes. This guide explores UK-licensed options, eligibility criteria, and how to find out which approach might work best for you. Use our free BMI calculator to check your starting point, then explore your options 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 Loss Medication Options
If you're looking for prescription weight loss medication in the UK, three medications are currently licensed for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections, whilst Saxenda is a daily injection.
- Mounjaro — dual GIP/GLP-1 agonist; clinical trials showed average weight loss of 15–21% of body weight at maximum dose
- Wegovy — GLP-1 agonist; average weight loss approximately 15% of body weight in clinical trials
- Saxenda — GLP-1 agonist; daily injection option for eligible adults
Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. You can use our GLP-1 weight loss calculator to estimate potential outcomes at different medication levels, though individual results vary significantly. All three medications are prescription-only and require a clinical assessment before being prescribed.
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 Weight Management vs Private Routes — How to Get Started
In the UK, you can access weight loss medication through two main routes: NHS specialist weight management services (tier 3 or tier 4) and private online prescribing. NHS access requires a referral from your GP to a specialist service in your region; availability and waiting times vary significantly across the country. Private prescribing offers faster access through GPhC-registered online pharmacies, but involves a cost (typically £129–£320+ per month depending on dose).
Start by speaking to your GP about whether nhs weight loss medication might be appropriate for you. They can assess your BMI, health conditions, and whether you meet eligibility criteria for NHS or private treatment. Your GP can also discuss lifestyle approaches, referrals to weight management services, and any combination of medication with diet and physical activity. Track your progress using our free progress tracker once you've started any programme.
- 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 best weight loss program for me personally?
The best programme depends on your BMI, health conditions, lifestyle, and preferences. Start by checking your BMI using our free calculator to understand your health category. Then speak to your GP, who can discuss NHS weight management services, prescription medication eligibility, or lifestyle-based programmes suited to your situation. Individual results vary significantly.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27 or above with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, etc.). For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply. A GP or licensed prescriber will assess your individual eligibility after a clinical evaluation.
What's the difference between NHS and private weight loss medication in the UK?
NHS medication is accessed through specialist weight management services (referral from GP, often long waiting lists, free on prescription once approved). Private medication is available through online pharmacies following a clinical assessment (faster access, costs approximately £129–£320+ per month). Both require a prescription from a UK-licensed prescriber and the same clinical assessment.
Can I combine weight loss medication with lifestyle changes?
Yes. Evidence shows that combining prescription medication with a reduced-calorie diet and increased physical activity produces the best results. Medication supports appetite control, but sustainable weight loss requires lifestyle changes alongside it. Your GP or prescriber will discuss the full approach during your assessment.
What weight loss results should I expect from medication?
Clinical trials showed average weight loss of 15–21% of body weight with prescription medications over several months, though individual results vary significantly. Some people lose more, some less. Results depend on dose, how long you take the medication, diet, physical activity, genetics, and other health factors. Track your progress with our free progress tracker.
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.