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
NHS Weight Loss Jabs — Complete UK Guide
Weight loss jabs, commonly called "slimming injections" in the UK, are prescription-only medications that may help support weight management in adults. These GLP-1 receptor agonist injections are available through the NHS, though access varies significantly by region. This guide explains how they work, who is eligible, and how to access them through NHS weight management services.
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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.
How NHS Weight Loss Jabs Work
NHS weight loss jabs contain medications like semaglutide (Wegovy) or tirzepatide (Mounjaro), which are GLP-1 receptor agonists. These injections mimic a natural gut hormone that helps regulate appetite and blood sugar control.
- They signal to your brain that you feel fuller after eating smaller meals
- They reduce cravings and hunger signals
- They slow how quickly food leaves your stomach
- Results vary individually — clinical trials showed average weight loss of 15–21% of body weight alongside reduced-calorie diet and increased physical activity
The NHS has approved these medications for weight management within specialist services. Access to prescription weight loss medication through the NHS is through tier 3 specialist weight management services, typically requiring referral from your GP. These are specialist multidisciplinary teams that assess your health comprehensively before prescribing.
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.
NHS Eligibility and Access
To access weight loss jabs through NHS specialist services, you typically need a BMI of 30 kg/m² or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply.
NHS availability varies significantly by region and local commissioning decisions. Waiting lists can be substantial in many areas. Ask your GP about referral to your local specialist weight management service to discuss whether prescription weight loss medication is suitable for you. Your GP can also discuss alternative approaches to weight management, including lifestyle changes and NHS digital programmes.
- 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 weight loss jabs and Ozempic?
Both Wegovy and Ozempic contain semaglutide, but Ozempic is licensed for type 2 diabetes management only, not weight loss. Wegovy is the licensed weight loss version. Using Ozempic for weight loss is off-label. Always use the medication licensed for the intended purpose.
How long do you stay on NHS weight loss jabs?
Duration depends on individual response and prescriber assessment. Some people continue long-term, others for set periods. Your specialist team will review your progress regularly and discuss whether to continue, adjust, or stop the medication based on your health and goals.
Can I get weight loss jabs through my GP, or do I need a specialist?
Weight loss jabs are prescribed through NHS specialist tier 3 weight management services, not standard GP practices. Your GP can refer you to these services, but specialist assessment is required before prescription.
What happens if the NHS waiting list is too long?
If NHS waiting times are lengthy, private online prescribing services offer faster access through UK-licensed prescribers. These require an online consultation and clinical assessment, then prescription through a GPhC-registered pharmacy — at personal cost.
Do weight loss jabs work for everyone?
Individual results vary significantly. Clinical trials show average weight loss of 15–21%, but some people see greater results, others smaller. Success depends on genetics, adherence to diet and activity changes, medical conditions, and other medications. Your prescriber will assess suitability for you personally.
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.