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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Diabetes Weight Loss Injection: What You Need to Know
Weight loss injections containing GLP-1 medication are now available in the UK for adults with type 2 diabetes or prediabetes who are overweight or obese. These prescription-only medicines, such as Wegovy (semaglutide), work by helping reduce appetite and supporting weight management alongside diet and exercise. If you have diabetes and are struggling with weight management uk, your GP can assess whether this treatment might be suitable for you. This guide explains how these injections work, who can access them, and what to expect.
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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.
How Diabetes Weight Loss Injections Work
GLP-1 receptor agonist medications mimic a natural hormone your body produces after eating. They signal to your brain that you feel full, which may help reduce appetite and food cravings. These injections also slow how quickly food leaves your stomach, supporting a feeling of fullness after smaller meals.
Wegovy (semaglutide) is the most commonly prescribed diabetes weight loss injection in the UK. It's a once-weekly injection that works alongside a reduced-calorie diet and increased physical activity. Clinical trials showed that on average, people using Wegovy at the maximum dose lost approximately 15% of their body weight over 68 weeks — though individual results vary significantly.
- Mechanism: GLP-1 hormone pathway activation
- Frequency: Once weekly injection
- Typical doses: 0.25 mg to 2.4 mg per week
- Results: Clinical trials showed average clinically studied weight loss
- Duration: Ongoing treatment while medication is taken
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.
Who Can Access Diabetes Weight Loss Injections in the UK
You may be eligible for prescription weight loss medication in the UK if you have a BMI of 30 or above, or 27 or above with at least one weight-related health condition — including type 2 diabetes or prediabetes. Access through the NHS is typically via specialist tier 3 weight management services, though waiting times vary significantly by region.
Private prescription through a registered UK prescriber is also available without NHS referral. Your GP or a licensed prescriber will assess whether this treatment is right for you based on your individual health, medications, and medical history. It's important to note these are prescription-only medicines requiring a clinical assessment before being prescribed. Try our free BMI calculator above to check your current BMI and understand where you stand on the scale.
- 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 Ozempic the same as Wegovy for weight loss?
Both contain the same active ingredient (semaglutide), but Ozempic is licensed only for type 2 diabetes management, not weight loss. Wegovy is the licensed weight loss version and is the correct prescription for weight management in the UK. Using Ozempic for weight loss is off-label.
How much weight can I expect to lose with a diabetes weight loss injection?
Clinical trials showed average weight loss of approximately 15% of body weight, though individual results vary significantly. Some people lose more, some less. Weight loss depends on your starting weight, diet, physical activity, and how your body responds to the medication.
Can I get a diabetes weight loss injection through the NHS?
Yes, NHS specialist weight management services can prescribe weight loss injections like Wegovy. Access is through referral from your GP to tier 3 services. However, availability and waiting times vary greatly by region. Private prescription is also available.
What are the main side effects of diabetes weight loss injections?
Common side effects include nausea, diarrhoea, constipation, and stomach pain — particularly when starting or increasing doses. These often improve over time. Serious side effects are rare but can include severe stomach pain (possible pancreatitis) requiring immediate medical attention.
Will I need to take a diabetes weight loss injection forever?
Weight loss injections are typically ongoing treatments. If you stop taking the medication, appetite tends to return and weight may be regained. Your GP or prescriber will discuss long-term management and whether this treatment is sustainable for you personally.
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.