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 Injections Online in the UK
Weight loss injections are prescription-only medications available in the UK for eligible adults seeking medical support for weight management. Three UK-licensed options—Mounjaro, Wegovy, and Saxenda—work by activating natural hunger-regulating pathways in your body. These injections are available both through the NHS and private online prescribing services, though access routes and eligibility differ. This guide explains how they work, who qualifies, and the difference between NHS and private access for weight loss injections online.
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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.
UK-Licensed Weight Loss Injections Explained
Three prescription weight loss injections are currently licensed in the UK:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist. Once-weekly injection with doses ranging from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks when combined with diet and exercise.
- Wegovy (semaglutide) — A GLP-1 receptor agonist. Once-weekly injection with doses from 0.25 mg to 2.4 mg. STEP trials demonstrated approximately 15% average weight loss at the maximum dose alongside reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — A GLP-1 receptor agonist. Once-daily injection with doses from 0.6 mg to 3 mg. Longer-established option with strong evidence base. All three work by reducing appetite, increasing fullness signals, and slowing how quickly food leaves your stomach. Individual results vary significantly.
Use our GLP-1 weight loss calculator to explore how these medications might fit into a weight management plan tailored to your circumstances.
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 vs Private Access in the UK
In the UK, weight loss injections are available through two routes. NHS access: Referral to a tier 3 specialist weight management service through your GP, though waiting lists are often lengthy and availability varies by region. Private access: Online consultation with a UK-licensed prescriber, prescription issued if clinically appropriate, dispensed by a GPhC-registered pharmacy. Private options are typically available faster but at personal cost (£120–£320 monthly depending on dose). Both routes require a clinical assessment to confirm eligibility: BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Your GP can discuss both options and help determine suitability for you.
- 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 are the eligibility criteria for weight loss injections in the UK?
Adults with a BMI of 30 kg/m² or above are generally eligible. Those with a BMI of 27–29.9 with weight-related conditions—such as type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease—may also qualify. South Asian, Chinese, Black African, and Black Caribbean adults have lower eligibility thresholds due to higher health risks at lower BMI levels. A prescriber will assess your individual circumstances.
Can I buy weight loss injections online in the UK without a GP referral?
Yes. Private online prescribing services allow you to complete a clinical consultation with a UK-licensed prescriber without NHS referral. If clinically appropriate, a prescription is issued and dispensed by a GPhC-registered pharmacy. NHS access requires GP referral to specialist services. Both routes involve clinical assessment—weight loss injections are prescription-only medicines.
How much weight can I expect to lose with these injections?
Clinical trials showed average weight loss of 15–21% of body weight, but individual results vary significantly. Weight loss depends on dose, adherence, diet, exercise, and personal factors. These medications work alongside lifestyle changes, not instead of them. Our GLP-1 weight loss calculator can help estimate potential outcomes based on different doses.
Are weight loss injections available on the NHS in all UK regions?
NHS availability varies significantly by region and depends on specialist tier 3 weight management service provision. Some areas have shorter waiting lists than others. Ask your GP about specialist services in your area. Private online prescribing is available throughout the UK without regional limitations.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed slightly higher average weight loss with Mounjaro, though both are effective. Mounjaro doses are larger (up to 15 mg weekly); Wegovy doses are smaller (up to 2.4 mg weekly). Both require assessment by a prescriber to determine which is appropriate 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.