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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NHS Weight Loss Advice: Medication and Support Options
If you're looking to lose weight in the UK, the NHS offers structured guidance and support across multiple tiers, including prescription weight management options for eligible adults. Weight management in the UK is increasingly supported by prescription medication alongside lifestyle changes. This guide explains what the NHS recommends, who can access medication, and how to start your weight loss journey with professional support.
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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
Three prescription medications are currently licensed in the UK for weight loss: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and GIP/GLP-1 receptor agonist injections that may help regulate appetite and support weight loss alongside diet and exercise.
Eligibility criteria: You may be eligible if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions including type 2 diabetes, high blood pressure, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher health risks at lower weights.
Clinical trial data shows Mounjaro may help participants lose an average of 15–21% of body weight, whilst Wegovy typically supports losses of around 15%, though individual results vary significantly. All prescription weight loss medications require a prescription and clinical assessment.
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.
Accessing Support: NHS Pathway vs Private Options
The NHS weight management pathway has four tiers: tier 1 (self-help and community programmes), tier 2 (GP-led interventions), tier 3 (specialist multidisciplinary services where prescription medication is typically initiated), and tier 4 (bariatric surgery). Prescription weight loss medication on the NHS is accessed through tier 3 specialist weight management services, usually requiring a GP referral.
NHS availability varies significantly by region, and waiting lists for specialist services can be lengthy. Many UK adults access prescription weight loss medication privately through registered online pharmacies following a clinical assessment with a UK-licensed prescriber. Your first step is to speak with your GP about your weight and whether specialist referral or private options might be appropriate for you. Use our free GLP-1 weight loss calculator to explore potential weight loss projections, and check your current BMI with our BMI calculator to understand where you sit on NHS eligibility criteria.
- 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 does the NHS recommend for weight loss?
The NHS recommends a calorie deficit of around 500 kcal per day for sustainable weight loss of 0.5–1 kg per week. This combines dietary changes with increased physical activity. For eligible adults, prescription medication like Mounjaro or Wegovy may be offered through specialist tier 3 services alongside these lifestyle changes. Your GP can advise what's appropriate for your individual situation.
How do I know if I'm eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related conditions such as type 2 diabetes, hypertension, or cardiovascular disease. For certain ethnic groups (South Asian, Chinese, Black African, Caribbean), lower thresholds apply. Speak to your GP about referral to a specialist weight management service in your area.
What's the difference between getting weight loss medication on the NHS versus privately?
NHS medication is accessed through tier 3 specialist services (usually via GP referral) and is free once prescribed, though availability and waiting times vary by region. Private prescription weight loss is accessed through online prescribers and registered pharmacies without NHS referral, is faster, but requires payment. Both require a clinical assessment before prescription.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both Mounjaro (tirzepatide) and Wegovy (semaglutide) are approved for NHS use within specialist tier 3 weight management services. However, access depends on local NHS availability and your GP's ability to refer you. Many areas have waiting lists. Ask your GP whether these are available in your region and whether you might be eligible for specialist referral.
What's the safe rate of weight loss the NHS recommends?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week for sustainable results. This rate reduces the risk of muscle loss, gallstones, and nutritional deficiency. Faster weight loss is possible with medical support, but should only be attempted under professional supervision. Aim for steady, long-term progress rather than rapid loss. ```
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.