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
How to Buy Weight Loss Injections in the UK
Weight loss injections are prescription-only medications available in the UK through NHS specialist services or private prescribing pathways. The most commonly prescribed options are Wegovy (semaglutide) and Mounjaro (tirzepatide), both licensed for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. Before buying any weight loss injection, you'll need a clinical assessment from a UK-licensed prescriber to confirm eligibility. This guide explains your options and how to access these medications safely and legally.
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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.
Understanding Weight Loss Injections Available in the UK
Weight loss injections are prescription-only medicines — you cannot buy them over the counter or without a prescription. Two main options are licensed for weight management in the UK: Wegovy (semaglutide), a GLP-1 receptor agonist, and Mounjaro (tirzepatide), which works via dual GIP and GLP-1 mechanisms. Both are once-weekly injections. Clinical trials show these medications may help with significant weight loss when combined with diet and exercise changes — for example, Wegovy demonstrated average weight loss of around 15% in the STEP trial, though individual results vary considerably. A third licensed option, Saxenda (liraglutide), is a daily injection. All three require a prescription and a clinical assessment to confirm you meet eligibility criteria before dispensing.
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.
How to Access Weight Loss Injections in the UK
You can access weight loss injections through two main routes in the UK. The NHS route involves referral from your GP to a tier 3 specialist weight management service — however, availability and waiting times vary significantly by region. The private route involves an online consultation with a UK-licensed prescriber, who will assess your medical history, current medications, and BMI to determine if treatment is appropriate. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Private prescribing typically offers faster access but comes at a cost, usually ranging from £129–£320 per month depending on the dose and medication. Regardless of route, a clinical assessment is always required — there is no option to buy without one.
- 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.
Is it legal to buy weight loss injections online in the UK?
Yes, it is legal to buy prescription weight loss injections online in the UK if you obtain a prescription from a UK-licensed prescriber following a clinical assessment. Online prescribers must be registered with the General Medical Council (GMC) and dispense through GPhC-registered pharmacies. Always check the prescriber's credentials and ensure the pharmacy is verified before purchasing.
How much do weight loss injections cost privately in the UK?
Private costs vary depending on the medication and dose. Wegovy and Mounjaro typically cost £129–£320 per month. Initial doses are lower and less expensive; maximum doses cost more. Some private providers offer subscription packages or tiered pricing. Always check the full cost including any consultation fees before committing.
Can I get weight loss injections on the NHS?
Yes, but access is limited to specialist tier 3 weight management services following a GP referral. Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions. Availability and waiting times vary significantly by region (NHS integrated care board). Contact your GP to enquire about referral options in your area.
What happens at a clinical assessment before buying weight loss injections?
A prescriber will review your medical history, current medications, allergies, BMI, blood pressure, and any existing health conditions. They'll ask about your weight loss goals and why you're interested in injections. This assessment confirms whether you meet eligibility criteria and whether the medication is safe for you. You may be asked to provide a GP contact or recent blood results.
Do I need to use a BMI calculator to confirm eligibility for weight loss injections?
Yes — you'll need to know your BMI to confirm eligibility. Use our free BMI calculator above to work out your exact BMI from your height and weight. A BMI of 30 or above generally qualifies you; if your BMI is 27–29.9, you'll need at least one weight-related health condition. Share your BMI with the prescriber during your assessment, or use our free weight converter to check your weight in different units first.
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.