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
Private Weight Loss Injections in the UK
Private weight loss injections are prescription-only medications available to eligible UK adults through private prescribing services. These GLP-1 and GIP/GLP-1 receptor agonist injections may help support weight management alongside diet and exercise. Three main options are licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). This guide explains how they work, who may be eligible, and how private access differs from NHS weight management services.
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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 Injection Options
Mounjaro (tirzepatide) is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. In clinical trials, it helped participants lose an average of 15–21% of body weight over 72 weeks, though individual results vary significantly. Wegovy (semaglutide) is a once-weekly GLP-1 injection with average weight loss of around 15% in clinical trials. Saxenda (liraglutide) is a once-daily GLP-1 injection and was the first weight loss injection licensed in the UK.
- All three are prescription-only and require a clinical assessment before being prescribed
- Each works by reducing appetite, increasing feelings of fullness, and slowing gastric emptying
- Doses are gradually increased over weeks to minimise side effects
- Most common side effects include nausea, diarrhoea, and constipation — these often improve over time
Try our free GLP-1 weight loss calculator to explore potential outcomes at different doses with any of these medications.
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: What's the Difference?
NHS access is through specialist tier 3 and 4 weight management services, typically following a GP referral. However, NHS availability varies significantly by region (integrated care board), and waiting lists can be very long in many areas. Private access is available through UK-licensed prescribers via regulated online services — no NHS referral needed. A clinical assessment is required to confirm eligibility based on your BMI and health conditions. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea, you may be eligible. Use our free BMI calculator to check your personal BMI and understand your starting point.
Whether you choose NHS or private weight management, a prescriber will assess whether prescription weight loss medication is suitable for you individually. This assessment includes your medical history, current medications, and weight management goals. Weight loss injections work best alongside a reduced-calorie diet and increased physical activity — they are not a replacement for lifestyle changes. Your GP can also advise on NHS options in your area, even if you choose to explore private prescribing. Track your progress using our free progress tracker whether you're accessing medication through the NHS or privately.
- 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.
How much do private weight loss injections cost in the UK?
Costs vary by provider and dose, ranging from approximately £129–£320 per month depending on which medication and which dose you're prescribed. This reflects the medication cost only — some providers may charge consultation fees. Always confirm total costs with your chosen service before starting treatment.
Can I get weight loss injections on the NHS?
Yes, the NHS has approved these medications through specialist weight management services (tier 3 and 4). However, access varies significantly by region and waiting lists can be lengthy. Ask your GP about NHS options in your area, or explore private prescribing if you wish to start sooner.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro clinical trials showed slightly higher average weight loss (15–21% vs 15%), but individual results vary. Both are once-weekly injections; your prescriber will advise which may be more suitable for you.
Who is eligible for private weight loss injections?
Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), may be eligible. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. A licensed prescriber will assess your individual eligibility.
Are there side effects I should know about?
Common side effects include nausea, diarrhoea, constipation, and stomach discomfort — these often improve over time as your body adjusts. Serious side effects are rare but can include pancreatitis or gallbladder problems. Always report any concerning symptoms to your prescriber. Detailed side effect information is provided with your prescription.
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.