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
Who Is Eligible For Weight Loss Injection in the UK?
Weight loss injections are prescription-only medications available in the UK for adults who meet specific eligibility criteria. Whether you can access prescription weight loss medication like Wegovy or Mounjaro depends on your BMI, any weight-related health conditions, and your ethnic background. This guide explains the exact eligibility thresholds set by NHS guidelines and how to find out if you qualify. Use our free BMI calculator above to check your personal BMI and understand where you fall on the eligibility spectrum.
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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 Eligibility Criteria For Weight Loss Injections
To be eligible for prescription weight loss injections in the UK, you must meet one of these criteria:
- BMI of 30 or above (regardless of health conditions)
- BMI of 27–29.9 with at least one weight-related health condition
Weight-related conditions that may qualify include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or a history of heart attack or stroke. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower eligibility thresholds: BMI 27.5 or above for obesity classification, and BMI 23–27.4 for overweight. This is because these populations face higher cardiovascular and diabetes risks at lower BMI levels. Calculate your BMI using our weight loss tool above to see where you stand against these thresholds.
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.
How To Access Weight Loss Injections in the UK
Access to prescription weight loss medication in the UK follows two main routes. Through the NHS, you'll typically need a referral from your GP to a specialist tier 3 weight management service, though availability varies significantly by region and waiting lists can be lengthy. Privately, you can access weight loss injections through a GPhC-registered online pharmacy following an online clinical assessment with a UK-licensed prescriber. Both routes require a prescriber to assess your individual health before issuing a prescription. Our GLP-1 weight loss calculator can help you understand how these medications work and their potential effects, based on clinical trial data.
What Happens During Your Eligibility Assessment?When you're assessed for weight loss injections, a healthcare professional will review your weight history, BMI, current health conditions, medications, and whether you're willing to make lifestyle changes. You'll also be asked about allergies, pregnancy plans (these medications aren't suitable during pregnancy), and your motivations for treatment. The prescriber will explain how GLP-1 weight management works, potential side effects, and that results vary between individuals. They may check your blood pressure and discuss your diet and exercise habits. Be honest about your medical history — this ensures any prescription is safe and appropriate for you. Individual results vary, and medication is most effective when combined with a reduced-calorie diet and increased physical activity.
- 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.
Do I need to be overweight for weight loss injections?
No — you need a BMI of 30 or above, or 27–29.9 with a weight-related health condition. These are medical obesity thresholds, not appearance-based. Calculate your BMI using our free tool to check your eligibility. For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply.
Can I get weight loss injections on the NHS?
Yes, through specialist tier 3 weight management services following a GP referral. However, NHS availability varies significantly by region and waiting lists can be very long. Private access is available through online prescribing services without an NHS referral, though this involves a cost.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes (not weight loss) and Wegovy is the licensed weight management version in the UK. Using Ozempic for weight loss is off-label. Wegovy is the prescription weight loss injection approved by the MHRA for weight management.
Do weight loss injections work for everyone?
Clinical trials show average weight loss of around 15% body weight with GLP-1 medication, but individual results vary significantly. Some people see greater results, others more modest results. These injections work best alongside a reduced-calorie diet and increased physical activity — they're not a standalone solution.
What if I'm not eligible now — can I reapply later?
Yes. If your BMI or health circumstances change, you can ask your GP for reassessment. You can also track your progress using our free progress tracker to monitor weight loss and health improvements over time. Some people become eligible as their circumstances evolve or they develop weight-related health conditions.
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.