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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Best Place to Inject Ozempic for Weight Loss
If you're considering semaglutide injections for weight loss in the UK, it's important to understand the correct injection sites and technique. This guide explains where to inject, how to rotate sites safely, and clarifies an important distinction: Ozempic is licensed for type 2 diabetes management, while Wegovy is the licensed weight management version in the UK. Both contain semaglutide, but only Wegovy is approved for weight loss. We'll cover safe injection practices, common site locations, and what you need to know before starting any prescription weight loss medication.
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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.
Where to Inject Semaglutide: Approved Injection Sites
Semaglutide injections for weight management (Wegovy) can be administered in three main locations:
- Stomach (abdomen) — the most commonly used site, injected into the fatty tissue 5cm away from the belly button
- Upper thigh — a convenient alternative site on the outer surface of the thigh
- Upper arm (back of the upper arm) — typically requires assistance from another person
All three sites use subcutaneous injection technique, meaning the needle goes into the fatty tissue just under the skin. Rotating between different areas is essential to prevent lipodystrophy (changes in fatty tissue at injection sites) and ensure consistent medication absorption. Your prescriber will demonstrate the correct injection technique, and it's vital to follow their guidance precisely. Using our free GLP-1 weight loss calculator can help you understand potential outcomes alongside proper injection technique for safe, effective weight management in the UK.
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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.
Important: Ozempic vs Wegovy for Weight Loss in the UK
A critical clarification: Ozempic is not licensed for weight loss in the UK. Ozempic (semaglutide up to 2mg) is approved only for type 2 diabetes management. Wegovy (semaglutide 2.4mg) is the licensed prescription weight loss injection in the UK. Using Ozempic off-label for weight loss is not recommended, and it's a common source of confusion. If you're interested in prescription weight loss medication in the UK, speak with your GP about accessing NHS weight loss services or a private licensed prescriber who can assess your eligibility. Both options require clinical assessment and a prescription. Your BMI, weight-related health conditions, and medical history will all factor into whether treatment is suitable 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.
Can I inject semaglutide anywhere on my body?
No, semaglutide for weight management should only be injected into three approved sites: the stomach, upper thigh, or back of the upper arm. Never inject into other body areas, as this could affect absorption and safety. Always follow your prescriber's instructions.
How often should I rotate my injection sites?
Rotate to a different injection site each week to prevent skin changes and lipodystrophy. If you inject in your stomach one week, choose your thigh the next week, then your arm, and repeat. This helps ensure consistent medication absorption over time.
Is Ozempic the same as Wegovy for weight loss?
No. Both contain semaglutide, but Ozempic is licensed for type 2 diabetes only (not weight loss in the UK), while Wegovy is the licensed weight management injection. Only Wegovy should be used for weight loss treatment. Clarify which medication your prescriber is recommending.
Does injection site pain mean I've done it wrong?
Mild redness, bruising, or slight discomfort at the injection site is normal. However, severe pain, swelling, or signs of infection require immediate medical attention. Contact your GP if you experience unusual reactions. Proper injection technique, demonstrated by your prescriber, minimises discomfort.
What's the difference between NHS and private weight loss medication access?
NHS access is through specialist tier 3/4 weight management services (often with waiting lists). Private access is via GPhC-registered online prescribers following a clinical assessment. Both require a prescription and clinical suitability assessment. Your GP can advise on NHS options in your region.
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.