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 Available in the UK
Weight management injections are prescription-only medicines now available in the UK for eligible adults. Also known as GLP-1 or GLP-1/GIP receptor agonist injections, these medications may help support weight loss when used alongside dietary changes and increased physical activity. This guide explains which injections are licensed in the UK, who may be eligible, how they work, and whether you can access them through the NHS or privately. If you're interested in weight management options, understanding what's available and speaking with your GP is a good first step.
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.
UK-Licensed Weight Loss Injections and How They Work
Three prescription weight loss injections are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist, activating two natural hormone pathways to help regulate appetite and support feeling fuller after meals
- Wegovy (semaglutide 2.4 mg) — a once-weekly GLP-1 injection that may help reduce food cravings and slow how quickly food leaves the stomach
- Saxenda (liraglutide) — a once-daily GLP-1 injection, the longest-established option for weight management in the UK
In clinical trials, these medications helped participants lose an average of 14–21% of their body weight over 12–18 months, though individual results vary significantly. They are always prescribed alongside a reduced-calorie diet and increased physical activity — the injections support lifestyle changes rather than replacing them. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses.
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 in the UK
To be eligible for prescription weight loss injections in the UK, you generally need a BMI of 30 or above, or 27–29.9 with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or heart disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have access at lower BMI thresholds due to higher health risks at the same weight.
NHS access is through specialist tier 3 weight management services, usually requiring a GP referral and assessment. Availability varies significantly by region, and waiting lists can be lengthy. Private access is available through registered online prescribers and pharmacies following a clinical consultation — no NHS referral needed. Your GP can advise which route is most suitable for you and help you understand your eligibility. Use our BMI calculator to check your current BMI category as a starting point for this conversation.
- 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.
Are weight loss injections available on the NHS?
Yes, Mounjaro, Wegovy, and Saxenda are available through NHS specialist weight management services (tier 3). However, availability varies by region and waiting times can be significant. You'll need a GP referral and assessment to access NHS treatment. Private prescribing is also available through registered online services.
How quickly do weight loss injections work?
Weight loss typically begins within the first 2–4 weeks, but the most significant results appear after 12–16 weeks of consistent use. Clinical trials showed average weight loss of 14–21% over 68–72 weeks. Results vary between individuals and depend on adherence, diet, and physical activity.
What are the most common side effects of weight loss injections?
Nausea, diarrhoea, constipation, and stomach pain are very common, especially when starting or increasing doses. These usually improve over time. Less common side effects include fatigue, dizziness, and headache. Serious side effects are rare but include severe stomach pain (possible pancreatitis) — seek immediate medical attention if this occurs.
Can I get weight loss injections if I have type 2 diabetes?
Yes, having type 2 diabetes actually increases eligibility for weight loss injections at lower BMI thresholds. Many people with type 2 diabetes use these medications, which can also help improve blood sugar control. Your prescriber will review your diabetes medications to ensure compatibility.
How do Mounjaro and Wegovy differ?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist and Wegovy (semaglutide) is a GLP-1-only agonist. Mounjaro clinical trials showed slightly higher average weight loss (20.9% vs 14.9%), but both are effective. Both are once-weekly injections. Your prescriber will assess which is more suitable based on your health profile and preferences. ```
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.