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 Injections and Other Options Available in the UK
If you're considering losing weight injections as part of your weight management journey, it's helpful to understand all the options available to you in the UK — from lifestyle approaches and NHS free support through to prescription medication and specialist services. Weight loss is rarely one-size-fits-all, and the right approach depends on your individual circumstances, health profile, and preferences. This guide explores the full range of weight loss methods, how to access them, and how to find the right fit for your situation.
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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.
Weight Loss Options Available in the UK
The UK health system offers a structured approach to weight management across four distinct tiers. Tier 1 (self-help) includes free online tools, self-guided programmes like the NHS Weight Loss Plan, and community support — no GP referral needed. Tier 2 brings primary care-based interventions, where your GP may refer you to behaviour change programmes, dietitian advice, or structured weight management groups in your local area.
Tier 3 (specialist services) is where prescription weight loss medications become available. These NHS services assess whether medications like Mounjaro (tirzepatide) or Wegovy (semaglutide) are appropriate for you. Access varies significantly by region and waiting lists can be lengthy. Tier 4 covers bariatric (weight loss) surgery — typically considered for people with severe obesity and significant health complications. Beyond the NHS, private prescription weight loss medication is also available in the UK through online services following a clinical assessment from a UK-licensed prescriber.
Use our free BMI calculator above to determine where your current weight sits within NHS health guidelines and discuss the best tier for your circumstances with your GP.
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.
Choosing the Right Weight Loss Approach for You
The best weight loss method is the one you can sustain over time. Consider these factors: your current BMI and health profile, any weight-related health conditions you have, how much support you need, your preferences (medication vs lifestyle-focused), and whether you prefer NHS or private routes. If you have a BMI of 30 or above, or 27 or above with weight-related conditions like type 2 diabetes or high blood pressure, you may be eligible for prescription medication through either route.
Start a conversation with your GP about your weight loss goals — they can assess your individual health, discuss which tier or approach suits you best, and refer you to appropriate support. You can also use our GLP-1 weight loss calculator to explore projected outcomes with different medication options, and our progress tracker to monitor your journey once you've chosen your path. Remember that sustainable weight loss typically combines dietary changes, physical activity, and behavioural support — medication is a tool to support these changes, not a replacement for them.
- 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 NHS and private weight loss medication in the UK?
NHS prescription medication is accessed through specialist tier 3 weight management services (referral from GP required) and is free once prescribed, but availability and waiting times vary by region. Private prescription weight loss medication is available through online services following a clinical assessment, doesn't require NHS referral, and costs typically £129–£320 per month depending on dose. Both require a prescription from a UK-licensed prescriber and both check your medical suitability before prescribing.
How do I know if I'm eligible for weight loss injections in the UK?
Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea), may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults may have eligibility at slightly lower BMI thresholds. You cannot take weight loss injections if you're pregnant, planning pregnancy, breastfeeding, or under 18. A prescriber will assess your full health profile before confirming eligibility.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with a maximum dose of 15 mg weekly, and clinical trials showed average weight loss of around 15–21% of body weight. Wegovy (semaglutide) is a GLP-1 agonist only, maximum dose 2.4 mg weekly, with average weight loss around 15% of body weight. Both are once-weekly injections. Individual results vary significantly, and either may be suitable depending on your health profile and how you respond.
Can I lose weight without medication?
Yes. Many people achieve sustainable weight loss through lifestyle changes alone — reducing calorie intake, increasing physical activity, and behaviour change support. The NHS recommends losing 0.5–1 kg per week as a safe, sustainable rate. A calorie deficit of around 500 kcal daily typically results in this loss. Our weight loss calculator and progress tracker can help you track lifestyle-based weight loss progress.
How do I start the conversation about weight loss with my GP?
Be honest about your weight concerns and any weight-related health issues you have (diabetes, high blood pressure, joint pain). Discuss what you've already tried and what approach appeals to you (medication vs lifestyle-focused). Ask your GP what tier 1 or tier 2 support is available locally, and whether you might be eligible for tier 3 specialist services or prescription medication based on your health profile.
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.