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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Free Online Weight Loss Support in the UK
Finding weight loss support in the UK doesn't have to cost you anything. The NHS offers free weight management services at different levels, and if you're eligible, prescription weight loss medication may be available through the NHS or private assessment. This guide covers your options, how to access support, and whether prescription treatments like Mounjaro or Wegovy might be suitable for you based on current UK guidelines.
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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 Options
If you're struggling with weight management in the UK, several prescription-only weight loss medications are now available through NHS specialist services or private prescribing. These include Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist, and Wegovy (semaglutide), a GLP-1 medication — both given as once-weekly injections. A third option, Saxenda (liraglutide), is a daily injection. All three are licensed in the UK for weight management in eligible adults.
Clinical trials show these medications can support significant weight loss: Mounjaro users lost an average of 15–21% of their body weight, while Wegovy users lost approximately 15% on average — though individual results vary considerably. Eligibility typically requires a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or heart disease. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher health risks at these levels.
Prescription weight loss medication works alongside a reduced-calorie diet and increased physical activity — it is not a replacement for lifestyle changes. Each medication requires a clinical assessment before being prescribed to ensure it's suitable for your individual health profile.
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 Get Started
In the NHS, prescription weight loss treatment is typically available through tier 3 specialist weight management services. You'll need a referral from your GP, and availability varies significantly by region and local integrated care board (ICB) decisions. Waiting lists can be lengthy in many areas.
Privately, you can access an online clinical assessment with a UK-licensed prescriber without an NHS referral — medications are then dispensed by GPhC-registered pharmacies. The first step, whether NHS or private, is a conversation with your GP about your weight, any health conditions, and what support might help. They can assess your eligibility, explain your options, and refer you to specialist services if appropriate. You can also use our free BMI calculator above to check your personal BMI and understand whether you may fall within eligibility ranges for prescription weight loss support.
To get the best free weight loss support in the UK, start with your GP — they're your gateway to NHS weight management services. Ask about Tier 1 and Tier 2 support first: community programmes, digital tools, and behaviour change services are all available at no cost and may be very effective. If you have a BMI of 30 or above, or 27–29.9 with health conditions, discuss whether specialist tier 3 services or prescription medication might be appropriate for you. Track your progress with our free progress tracker to monitor changes over time, and use our GLP-1 weight loss calculator to understand potential outcomes if prescription medication becomes an option. Remember: sustainable weight loss involves both changes to eating habits and increased physical activity, and individual results vary based on many factors including genetics, medical history, and lifestyle adherence.
- 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.
Is weight loss medication available free on the NHS in the UK?
Yes, weight loss medications like Mounjaro and Wegovy can be prescribed through NHS specialist tier 3 weight management services, but access varies by region and requires a GP referral. Waiting lists can be long. Some people access these medications privately without NHS involvement.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) works on the GLP-1 pathway only. Clinical trials show both can support weight loss of 15–21% of body weight on average. Both are once-weekly injections. Individual response varies.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (diabetes, high blood pressure, heart disease) may be eligible. Lower BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. A prescriber will assess your individual eligibility.
Can I get online weight loss support without medication?
Yes. The NHS offers free tier 1 and tier 2 weight management support including digital tools, community programmes, and behaviour change coaching. These are available through your GP without cost and don't involve medication.
How do I start getting weight loss support from my GP?
Contact your GP surgery and explain you're looking for weight management support. They'll assess your health, discuss your BMI, check for any weight-related health conditions, and refer you to appropriate services — either community weight management or specialist tier 3 services if you're eligible for prescription options.
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.