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
Weight Loss in the UK — Your Complete Health Guide
Weight loss in the UK is supported by multiple evidence-based pathways, from lifestyle changes to prescription medication options. The NHS recommends sustainable approaches that combine dietary changes with increased physical activity, helping adults lose weight at a safe rate of 0.5 to 1 kg per week. Whether you're exploring self-managed weight loss, seeking NHS support, or considering prescription treatments like GLP-1 injections, understanding your options and eligibility is the first step towards meaningful, lasting results aligned with UK health guidance.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Weight Loss Pathways and NHS Support
The NHS provides a structured four-tier weight management pathway designed to support adults at different stages. Tier 1 focuses on self-help tools and community programmes, including digital resources and the NHS Weight Loss Plan—ideal for starting your weight loss journey independently. Tier 2 involves primary care-based interventions where your GP can offer behavioural support and structured programmes. Tier 3 is specialist multidisciplinary weight management services, where prescription medications like Mounjaro (tirzepatide) or Wegovy (semaglutide) may be prescribed following clinical assessment. Tier 4 covers bariatric surgery for severe obesity with significant health complications. Access varies by region and ICB (Integrated Care Board), so contacting your GP about local services is essential. Use our free BMI calculator above to understand your current BMI category and discuss which tier of support might suit you with your healthcare provider.
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.
Medication Options and Healthy Lifestyle Foundations
Prescription weight loss medications—including GLP-1 receptor agonist injections—are available in the UK for 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. Wegovy (semaglutide) is a once-weekly injection that works by regulating appetite; clinical trials showed average weight loss of around 15% of body weight alongside diet and exercise. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with average trial results of 15–clinically studied weight loss. Both are prescription-only and require a clinical assessment before being prescribed. Medications work best alongside sustainable lifestyle changes—our GLP-1 weight loss calculator can help estimate potential outcomes at different doses. Remember, individual results vary, and a reduced-calorie diet combined with regular physical activity remains fundamental to any weight loss approach.
- 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's the healthy rate of weight loss according to the NHS?
The NHS recommends losing 0.5 to 1 kg (1–2 lbs) per week for sustainable weight loss. This typically requires a calorie deficit of approximately 500 kcal per day. Faster loss may lead to muscle loss and is harder to sustain long-term without medical supervision.
How do I access weight loss medication through the NHS in the UK?
You'll need referral from your GP to a specialist tier 3 weight management service. Eligibility requires a BMI of 30 or above, or 27+ with weight-related health conditions. Availability varies significantly by region, and waiting lists can be lengthy. Your GP can advise on local services and timescales.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Wegovy is specifically licensed for weight management in the UK (doses up to 2.4 mg weekly). Ozempic is licensed for type 2 diabetes (doses up to 2 mg) and is not approved for weight loss. Using Ozempic for weight loss would be off-label prescribing.
Can I get weight loss injections privately in the UK without NHS referral?
Yes. Private GLP-1 prescriptions are available through UK-licensed prescribers via online consultations with GPhC-registered pharmacies. These don't require NHS referral but do require clinical assessment. Costs typically range from £129–£320 monthly depending on dose.
What lifestyle changes support weight loss alongside medication?
A reduced-calorie diet, increased physical activity, and behavioural changes are essential. Evidence supports Mediterranean-style eating, intermittent fasting, or low-carbohydrate approaches—choose what's sustainable for you. Track your progress using our free progress tracker to stay motivated and accountable.
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.