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 Injections on the NHS — How to Access Them
Weight loss injections are prescription-only medicines available through the NHS and private clinics in the UK. The most commonly prescribed weight loss injections for nhs weight management are GLP-1 receptor agonists like semaglutide (Wegovy) and tirzepatide (Mounjaro), which may help reduce appetite and support sustainable weight loss when used alongside dietary changes and increased physical activity. Access and availability vary by region, so understanding your options is important if you're considering this form of treatment.
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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 Weight Loss Injections Work on the NHS
Weight loss injections licensed in the UK include Wegovy (semaglutide) and Mounjaro (tirzepatide), both prescription-only medicines that work as GLP-1 receptor agonists. These medications may help reduce appetite, support feeling fuller after smaller meals, and assist with lose weight safely by slowing how food moves through your stomach. Clinical trials showed that semaglutide helped adults lose an average of approximately 15% of their body weight — though individual results vary significantly. Tirzepatide, a dual GIP and GLP-1 agonist, showed average weight loss of 15–21% in clinical trials.
Weight loss injections are not a structured approach — they're most effective when combined with a reduced-calorie diet, increased physical activity, and behaviour change support. The NHS emphasises that nhs weight loss programmes work best when patients are committed to lifestyle modifications alongside medication.
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.
Eligibility and How to Access Weight Loss Injections via the NHS
NHS access to weight loss injections is through tier 3 specialist weight management services, not standard GP prescription. You may be eligible if you have a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply.
To access NHS treatment, ask your GP for a referral to your local specialist weight management service. However, waiting lists can be lengthy — in some areas, NHS access is limited due to demand. Private prescription weight loss is also available through GPhC-registered online prescribers following a clinical assessment, offering faster access but at a cost.
Calculate your current BMI using our free BMI calculator above to see where you stand against NHS healthy weight guidelines. You can also use our GLP-1 weight loss calculator to estimate potential results at different doses, and track your progress throughout your weight loss journey with our free progress tracker. These tools help you understand your starting point and set realistic, evidence-based goals for sustainable weight loss in the UK.
- 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 Wegovy and Ozempic?
Both contain semaglutide, but Ozempic is licensed for type 2 diabetes (up to 2 mg dose). Wegovy is the licensed weight management version (up to 2.4 mg). Only Wegovy should be used for weight loss in the UK — using Ozempic for weight loss is off-label and not recommended. Always ensure your prescriber gives you the correct licensed medication.
How long does it take to see weight loss results from injections?
Most people notice appetite changes within 1–2 weeks, but significant weight loss typically takes 4–12 weeks to become noticeable. Clinical trials measured results over 68–72 weeks. Weight loss is gradual and sustainable — the NHS recommends losing 0.5–1 kg per week as a safe, achievable rate alongside lifestyle changes.
Are weight loss injections available on the NHS everywhere in the UK?
Availability varies significantly by region and NHS trust. Some areas have good access through specialist weight management services; others have long waiting lists or limited availability. Contact your GP to ask about local tier 3 weight management services. Private access via online prescribers is faster but involves a cost.
What are the common side effects of weight loss injections?
The most common side effects are nausea, diarrhoea, constipation, and stomach pain — these often improve over time as your body adjusts. Less common side effects include fatigue, dizziness, and injection site reactions. Serious side effects are rare but can include pancreatitis symptoms. Your prescriber will discuss all risks and monitor you during treatment.
Can I use weight loss injections if I have type 2 diabetes?
Yes, weight loss injections are often suitable for people with type 2 diabetes, as they help manage both weight and blood sugar. However, if you're taking other diabetes medications like insulin or sulphonylureas, your prescriber may need to adjust your doses. Always inform your prescriber of all your current medications before starting weight loss injections.
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.