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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Weight Loss Resources in the UK — Your Medication Guide
Finding the right weight loss resources in the UK can feel overwhelming, but help is available through both NHS and private routes. Whether you're looking to understand your BMI, convert your weight between different measurements, or explore prescription medication options, this guide covers the key weight management resources available to you. We'll walk you through UK-licensed medication options, eligibility criteria, and how to access support through your GP or private healthcare providers.
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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
Three prescription-only medicines are currently licensed in the UK for weight management in adults with obesity or overweight with related health conditions:
- Mounjaro (tirzepatide) — a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. Clinical trials showed adults lost an average of 15–21% of their body weight over 72 weeks alongside lifestyle changes.
- Wegovy (semaglutide) — a once-weekly GLP-1 receptor agonist. STEP trial data demonstrated average weight loss of around 14.9% body weight at the maximum dose.
- Saxenda (liraglutide) — a daily GLP-1 injection, the original UK-licensed weight loss medication option.
All three are prescription-only and require clinical assessment before being prescribed. Eligibility typically requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. Individual results vary significantly, and medication works best alongside a reduced-calorie diet and increased physical activity. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses.
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 Weight Loss Support — NHS vs Private Routes
In the UK, you can access prescription weight loss medication through two main pathways:
- NHS route: Referral to a specialist tier 3 weight management service via your GP. NICE has approved tirzepatide and semaglutide for eligible adults, but availability varies significantly by region. Waiting times can be lengthy in many areas.
- Private route: Online consultation with a UK-licensed prescriber registered with the GPhC. If clinically appropriate, a prescription is issued and dispensed by a regulated pharmacy, without requiring NHS specialist referral.
Start by discussing weight management options with your GP, who can assess your eligibility and refer you to appropriate services. Your GP can also advise whether prescription medication is suitable alongside any other health conditions or medications you take. Use our free BMI calculator to understand your current BMI category and take this information to your appointment.
- 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 difference between GLP-1 and GIP/GLP-1 medications?
GLP-1 receptor agonists (like Wegovy and Saxenda) activate one hormone pathway to reduce appetite and support satiety. Mounjaro is a dual GIP/GLP-1 agonist, activating two pathways simultaneously, which may provide enhanced results. Both work by signalling fullness to your brain and slowing gastric emptying.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires BMI ≥30 kg/m², or BMI 27–29.9 with weight-related conditions like type 2 diabetes or high blood pressure. For South Asian, Chinese, Black African, and Black Caribbean adults, lower thresholds apply. Your GP can assess your individual eligibility and refer you to specialist services if appropriate.
How quickly will I lose weight on GLP-1 medication?
Clinical trials showed average weight loss of 14–21% body weight over several months, but individual results vary considerably. The NHS recommends losing 0.5–1 kg per week for sustainable results. Weight loss occurs gradually and works best alongside reduced-calorie diet and physical activity. Use our weight loss calculator to estimate potential outcomes.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both are NICE-approved for use in NHS specialist weight management services. However, availability varies by region and waiting lists can be long. Private access through online prescribers is also available without NHS referral. Your GP can explain both pathways and help you find local services.
What's the best way to track weight loss progress?
Track using consistent measurements — use our free weight converter to convert between kg, stone, and pounds for consistency. Our progress tracker tool lets you log weekly or monthly changes and visualize trends over time. Also measure your waist circumference and note how clothes fit, as muscle gain can offset fat loss on the scales.
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.