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 Jabs in the UK — NHS & Prescription Options
Weight loss jabs—also called slimming injections or GLP-1 medications—are now available to eligible adults in the UK through both NHS specialist services and private prescription. These once-weekly injectable medications can support weight management for adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. Understanding your options, eligibility criteria, and how to access these treatments through NHS or private pharmacies is the first step toward getting the support you need.
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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.
UK-Licensed Weight Loss Injections & How They Work
Three prescription-only weight loss injections are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide)—a dual GIP/GLP-1 receptor agonist, dosed from 2.5mg to 15mg once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight alongside reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide)—a GLP-1 receptor agonist, dosed from 0.25mg to 2.4mg once weekly. The STEP trials demonstrated average weight loss of approximately 15% body weight at the highest dose.
- Saxenda (liraglutide)—a daily GLP-1 injection (0.6mg to 3mg), an alternative for those preferring daily over weekly dosing.
Each medication works by activating hormone pathways that reduce appetite, support feeling fuller after eating, and slow gastric emptying. Results vary between individuals, and all are most effective when combined with lifestyle changes. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and check your BMI using our calculator to confirm eligibility 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.
NHS Access vs Private Prescription — Which Route Is Right for You?
NHS Route: Weight loss medication is available through NHS specialist tier 3 weight management services, typically following referral from your GP. NICE has approved tirzepatide (Mounjaro) and semaglutide (Wegovy) for NHS use. However, availability and waiting times vary significantly by region. Contact your GP to ask about tier 3 weight management services in your area—some regions have long waiting lists.
Private Route: Licensed UK prescribers can assess you for weight loss medication online without NHS referral. Prescriptions are dispensed by GPhC-registered pharmacies. This route is usually faster but involves private costs (typically £129–£320 monthly depending on dose). Both routes require a clinical assessment to confirm eligibility and rule out contraindications.
Whichever route you choose, prescription weight loss is part of a comprehensive approach to weight management.
- 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 makes someone eligible for weight loss jabs in the UK?
Adults with a BMI of 30 or above are generally eligible. Those with a BMI of 27–29.9 may be eligible if they have a weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, high cholesterol, sleep apnoea, or cardiovascular disease). Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds applied. Your GP or prescriber will assess your individual circumstances.
How long does it take to see weight loss results from these injections?
Most people begin to notice weight changes within 4–8 weeks, though the dose is gradually increased over weeks 1–20. Full benefits are typically seen at 12–16 weeks. However, individual results vary—some people lose more, some lose less. These medications work best alongside a reduced-calorie diet and increased physical activity.
Can I get weight loss jabs through my GP without waiting for a specialist referral?
Standard GP prescriptions for weight loss injections are uncommon—these medications are typically initiated through NHS tier 3 specialist weight management services or via private online prescription from a UK-licensed prescriber. Ask your GP about specialist services available in your area, or explore private prescription options if you prefer faster access.
Are weight loss injections safe? What are the main side effects?
These medications are prescription-only and licensed by the MHRA, but like all medicines, they have side effects. Common ones include nausea, diarrhoea, constipation, and stomach discomfort—often mild and temporary. Serious side effects are rare but can include severe stomach pain (pancreatitis) or gallbladder problems. Always discuss risks and benefits with your prescriber before starting treatment.
How much do weight loss jabs cost privately in the UK?
Costs vary by dose, medication, and provider but typically range from £129 to £320+ per month. Starting doses (e.g., 2.5mg Mounjaro or 0.25mg Wegovy) are at the lower end; maximum doses cost more. Some private providers offer loyalty discounts or payment plans. Ask for a full cost breakdown before starting, as you'll need consistent access to the full treatment course.
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.