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
Free tracker included with every download this week
Medical Weight Loss Programs in the UK
Medical weight loss programs in the UK range from NHS-supported services to private prescription options. If you're looking to lose weight and have a BMI of 30 or above (or 27+ with weight-related health conditions), you may be eligible for prescription weight management support. The NHS offers a structured tier-based approach, while private options including GLP-1 weight loss injections like Mounjaro and Wegovy are also available. Our free BMI calculator can help you check your starting point, and understanding your options is the first step toward sustainable weight management.
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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.
NHS Weight Management Pathways Explained
The NHS provides four-tier weight management pathways for eligible adults:
- Tier 1: Self-help tools, community weight loss programmes, and digital resources like the NHS Weight Loss Plan
- Tier 2: Primary care interventions — your GP may refer you to structured behaviour change programmes
- Tier 3: Specialist weight management services where prescription weight loss medications may be offered alongside dietary and lifestyle support
- Tier 4: Bariatric surgery services for severe obesity with significant health complications
Access to each tier typically requires a GP referral. NHS availability varies significantly by region — some areas have shorter waiting times than others. Tier 3 specialist services are where GLP-1 medications like Wegovy (semaglutide) may be prescribed, though access is limited and waiting lists can be substantial in many regions. Your GP can advise which tier is appropriate for your situation and local availability.
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.
Private Medical Weight Loss Options
Private weight loss programs and prescription medications offer faster access without NHS waiting lists. GLP-1 weight loss injections — including Mounjaro (tirzepatide) and Wegovy (semaglutide) — are available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber. These medications may help reduce appetite and support weight loss alongside a reduced-calorie diet and increased physical activity. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses. Private options typically cost £129–£320 per month depending on the medication and dose. Unlike NHS services, private prescription weight loss doesn't require a GP referral, making it accessible for those seeking faster treatment initiation.
- 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 a medical weight loss program?
A medical weight loss program uses prescription medications, clinical supervision, and lifestyle support to help achieve weight loss. In the UK, medical programs are available through the NHS (via specialist services) or privately through licensed prescribers. Medications may include GLP-1 receptor agonists like Wegovy or Mounjaro, which help regulate appetite.
Am I eligible for prescription weight loss treatment on the NHS?
Generally, you may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition like type 2 diabetes or high blood pressure. Access is through specialist tier 3 services via GP referral. However, NHS availability is limited and varies by region. Your GP can assess your eligibility.
What's the difference between Mounjaro and Wegovy?
Both are prescription-only weight loss injections available once weekly. Mounjaro (tirzepatide) activates two hormone pathways (GIP and GLP-1), while Wegovy (semaglutide) activates one (GLP-1 only). In clinical trials, Mounjaro showed average weight loss of 15–21% of body weight, while Wegovy showed approximately 15%. Individual results vary significantly.
How much do private weight loss programs cost in the UK?
Private GLP-1 injections typically cost £129–£320 per month depending on dose and provider. Costs vary based on medication choice (Mounjaro, Wegovy, or Saxenda). Some private providers offer payment plans. NHS services are free, though waiting lists can be lengthy.
Can I use our free progress tracker to monitor my weight loss journey?
Yes. Our free progress tracker allows you to log your weight weekly or monthly and track your progress visually over time. This is helpful whether you're following an NHS program, using prescription medications, or making lifestyle changes. Monitoring progress supports motivation and accountability throughout your weight loss journey.
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.