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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Diabetic Diets for Weight Loss and Prescription Medication in the UK
If you have type 2 diabetes or prediabetes and are looking to lose weight, dietary changes are important — but prescription weight management options may also be available to you. In the UK, several medications are approved specifically to help adults with diabetes lose weight alongside dietary modifications. This guide explains how NHS weight management works, what prescription options exist, and how to find out if you're eligible for treatment. Weight loss of even 5–10% of your body weight can significantly improve blood sugar control and reduce diabetes-related health risks.
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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 Prescription Weight Loss Options for Diabetes
For adults with type 2 diabetes or prediabetes, prescription weight loss medications are available in the UK if you meet eligibility criteria. Three main options are licensed for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection, dual GIP and GLP-1 agonist, average weight loss 15–21% in clinical trials
- Wegovy (semaglutide) — a once-weekly GLP-1 injection, average weight loss around 15% in trials
- Saxenda (liraglutide) — a daily GLP-1 injection, average weight loss around 5–6kg in trials
All three are prescription-only medicines requiring clinical assessment. They work alongside reduced-calorie diets and increased physical activity — not instead of lifestyle changes. Our free GLP-1 weight loss calculator can help you understand potential weight loss projections at different doses. Eligibility typically requires a BMI of 30 or above, or 27 or above if you have weight-related health conditions like diabetes or hypertension.
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 Access vs Private Prescription in the UK
In the UK, you can access prescription weight loss medication through two routes:
- NHS: Referral to a tier 3 specialist weight management service through your GP. Availability varies significantly by region, and waiting lists can be lengthy. NICE has approved tirzepatide (Mounjaro) for use within specialist services.
- Private: Online consultation with a UK-licensed prescriber, prescription issued if clinically suitable, dispensed by a GPhC-registered pharmacy. Available without NHS referral, though costs apply (typically £129–£320+ monthly depending on dose).
To find out if you're eligible, speak with your GP about your weight loss goals and any diabetes-related health concerns. They can assess your individual circumstances and discuss whether prescription medication might support your weight management journey. Use our free BMI calculator to check your current BMI before your appointment — this information will be helpful in your discussion.
- 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, adults with type 2 diabetes may be eligible for prescription weight loss injections like Mounjaro or Wegovy if they meet BMI criteria (typically 30+, or 27+ with diabetes). These medications help regulate blood sugar and support weight loss. Eligibility is assessed individually by a prescriber or GP.
How much weight can I expect to lose with prescription medication and a diabetic diet?
Clinical trials show average weight loss of 15–21% body weight with Mounjaro and around 15% with Wegovy, alongside dietary changes. Individual results vary significantly. Even modest weight loss (5–10%) can improve blood sugar control and reduce diabetes complications.
Do I need a GP referral to get prescription weight loss medication in the UK?
For NHS access, yes — you'll need a GP referral to a specialist tier 3 weight management service. For private prescriptions, you can consult directly with a UK-licensed online prescriber without a GP referral, though discussing with your GP is still recommended.
What's the difference between a diabetic diet and using weight loss medication?
A diabetic diet focuses on blood sugar control through carbohydrate management and balanced nutrition. Weight loss medications (GLP-1 agonists) reduce appetite and support feeling fuller. Both work together — medication supports dietary changes, not replaces them.
How long does it take to see weight loss results with prescription medication?
Weight loss typically begins within 4–8 weeks, though individual timelines vary. Most significant weight loss occurs between weeks 8–20 as doses are gradually increased. Progress can be tracked using our free progress tracker alongside regular GP check-ins.
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.