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
Diabetic Weight Loss Diet — UK Medication Options
Weight management is particularly important for adults with type 2 diabetes or prediabetes, as losing even 5–10% of body weight can significantly improve blood sugar control. Beyond dietary changes and increased physical activity, prescription weight loss medications are now available in the UK for eligible adults. This guide explains the medication options, how they work, and how to find out if you qualify through the NHS or private prescription routes.
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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 Medications for Diabetes
Three prescription medications are currently licensed in the UK for weight management and are suitable for adults with type 2 diabetes or prediabetes:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. Average weight loss in clinical trials was approximately 15–21% of body weight over 72 weeks when combined with dietary changes.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. Clinical trials showed average weight loss of around 15% of body weight at the maximum dose.
- Saxenda (liraglutide) — a GLP-1 receptor agonist given as a daily injection. Slightly lower average weight loss compared to the once-weekly options, but still effective for eligible adults.
All three medications work by helping regulate appetite, reduce food cravings, and support feeling fuller after smaller meals. Individual results vary, and these medications are prescribed alongside a reduced-calorie diet and increased physical activity, not as a replacement for lifestyle changes.
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 Eligibility and Accessing Treatment
To be eligible for prescription weight loss treatment in the UK, you generally need a BMI of 30 or above, or 27 or above if you have weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, or sleep apnoea. Check your BMI using our free BMI calculator above to see where you fall.
On the NHS, access is through specialist tier 3 weight management services — not routine GP prescription. You'll typically need a referral from your GP, though availability varies significantly by region and waiting lists can be lengthy. Private prescription routes are also available through registered online services following a clinical assessment, though these involve out-of-pocket costs. Speak to your GP to discuss your weight management goals and options available in your area.
- 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 use weight loss injections if I have type 2 diabetes?
Yes. GLP-1 and GIP/GLP-1 medications like Mounjaro and Wegovy are suitable for adults with type 2 diabetes or prediabetes and are specifically recommended as weight management options. However, if you take insulin or other diabetes medications, your doses may need adjusting — always inform your prescriber of all current medications.
How much weight can I expect to lose?
Clinical trials show average weight loss of 15–21% of body weight depending on the medication and dose. However, individual results vary significantly. Some people lose more, some less. Weight loss is achieved alongside dietary changes and increased physical activity, not medication alone. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
What's the difference between NHS and private prescription weight loss treatment?
NHS treatment is free but accessed through specialist services with referral and often significant waiting lists. Private prescription is quicker and doesn't require a waiting list but costs approximately £129–£320 per month depending on the medication and dose. Both require a clinical assessment and prescription from a UK-licensed prescriber.
How do I find out if I'm eligible?
Calculate your BMI using our free BMI calculator on this page. If your BMI is 30 or above, or 27–29.9 with a weight-related health condition like diabetes, you may be eligible. Book a GP appointment to discuss your weight management options and ask about referral to specialist services or private prescription routes available to you.
Are weight loss injections suitable alongside diabetes medication?
Yes, they're often prescribed alongside diabetes medication. GLP-1 medications can actually help improve blood sugar control. However, medications like insulin and sulphonylureas may need dose adjustments to prevent low blood sugar. Always tell your prescriber about all medications you take, and your diabetes team will monitor you closely.
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.