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 Injection Options Available in the UK
If you're exploring ways to lose weight in the UK, injections are just one option among many approaches. Weight loss injections are prescription-only medicines that may help support weight management when used alongside lifestyle changes. But before considering any injection, it's important to understand all the options available to you—from free NHS support through to specialist services and prescription medications. This guide covers the full range of safe, evidence-based weight loss methods available in the UK today.
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.
Weight Loss Options in the UK — From Lifestyle to Specialist Services
The NHS recognises weight management as a stepped approach, with different levels of support available depending on your needs and circumstances.
Tier 1 (Self-help and community support): Free resources including the NHS Weight Loss Plan, digital apps, and community weight management programmes. These are available to all UK adults without referral.
Tier 2 (Primary care interventions): Support through your GP, including behaviour change programmes, diet advice, and physical activity support. Your GP can assess your health and eligibility.
Tier 3 (Specialist weight management): Multidisciplinary services led by specialist teams. This is where prescription weight loss medications—including weight loss injections—are assessed and prescribed. Access typically requires a GP referral, though availability varies significantly by region.
Tier 4 (Bariatric surgery): Surgical options for severe obesity with significant health complications. Assessed by specialist teams.
In addition to the NHS pathway, prescription weight loss injections are also available through private online prescribing services following a clinical assessment. Use our free BMI calculator above to see where you fall on the NHS BMI guidance, which can help inform conversations with your GP about next steps.
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.
Types of Weight Loss Injections Available in the UK
Currently licensed weight loss injections available in the UK include Mounjaro (tirzepatide)—a once-weekly injection with dual GIP and GLP-1 action—and Wegovy (semaglutide)—a once-weekly GLP-1 injection. Clinical trials showed average weight loss of 15–21% with Mounjaro and approximately 15% with Wegovy, though individual results vary significantly.
Both are prescription-only medicines requiring clinical assessment before prescription. They work best alongside reduced-calorie diet and increased physical activity—they're not standalone solutions. Try our free GLP-1 weight loss calculator to explore potential weight loss projections at different doses, and our progress tracker to monitor your journey if you do start treatment.
These injections are not suitable for everyone; your prescriber will assess your health, medical history, and eligibility during a consultation.
- 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 injection access in the UK?
NHS access is through specialist tier 3 weight management services, typically requiring a GP referral and subject to regional availability—waiting lists can be lengthy. Private access is through UK-licensed online prescribers following a clinical assessment, available without NHS referral but at a cost. Both pathways require a prescription and clinical evaluation.
Do weight loss injections work without diet and exercise changes?
No. Weight loss injections are most effective when combined with a reduced-calorie diet and increased physical activity. They support these lifestyle changes by helping reduce appetite and food cravings, but they're not a substitute for lifestyle modification.
How quickly will I lose weight with a weight loss injection?
The NHS recommends sustainable weight loss of 0.5–1 kg per week. Weight loss with prescription injections typically becomes noticeable after 4–8 weeks, but individual results vary. Your prescriber will monitor your progress and adjust doses if needed.
Are weight loss injections suitable for everyone?
No. You must meet eligibility criteria (typically BMI 30+ or 27+ with health conditions), be aged 18 or over, and not be pregnant, planning pregnancy, or breastfeeding. A clinical assessment will determine suitability based on your individual health profile.
What if weight loss injections aren't right for me—what are other options?
Many approaches exist. Free NHS resources like the Weight Loss Plan are a good starting point. Your GP can discuss behaviour change support, dietary approaches, or referral to tier 2 or 3 services. Some people benefit from structured diet programmes, increased physical activity, or working with a dietitian. Your GP can help identify the best approach for you.
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.