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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Graph For Weight Loss — UK Prescription Medication Guide
A weight loss graph helps you visualise your progress over time and stay motivated during your weight management journey. If you're considering prescription weight loss medication in the UK, understanding the expected trajectory and how different treatments compare can help you make informed decisions. This guide covers the prescription options available through the NHS and privately, eligibility criteria, and how to discuss weight management with your GP.
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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.
UK-Licensed Prescription Weight Loss Medications
Three prescription medications are currently licensed in the UK for weight management in adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro is a dual GIP and GLP-1 receptor agonist that may help with appetite regulation and weight management. Wegovy is a GLP-1 receptor agonist taken once weekly. Saxenda is a daily GLP-1 injection. Clinical trials show average weight loss ranging from approximately 15% to 21% of body weight with Mounjaro and around 15% with Wegovy—though individual results vary significantly. Eligibility typically requires a BMI of 30 kg/m² or above, or 27 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply. All three are prescription-only medicines requiring assessment by a healthcare professional.
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 and Next Steps
In the UK, prescription weight loss medication can be accessed through two routes. NHS access is through specialist tier 3 weight management services—your GP can refer you, though waiting times vary significantly by region and service availability. Private access is available through UK-licensed online prescribing services following a clinical assessment. Both routes require a prescription from a licensed prescriber. Use our free GLP-1 weight loss calculator to estimate potential weight loss at different doses, and our free BMI calculator to check your starting point. Start the conversation with your GP about weight management options, your health goals, and whether prescription medication might be appropriate for you alongside lifestyle changes such as reduced-calorie diet and increased physical activity.
- 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.
What does a typical weight loss graph look like with Mounjaro or Wegovy?
In clinical trials, weight loss typically begins within the first 4 weeks and progresses steadily over 12–20 weeks as doses are increased. Most participants reach their maximum weight loss at around 52–68 weeks. The graph shows a gradual downward curve rather than dramatic drops. Individual progression varies—some people plateau earlier, others continue losing weight longer.
Am I eligible for prescription weight loss medication through the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. For certain ethnicities, lower thresholds apply. Your GP can assess your eligibility and refer you to specialist services if appropriate.
How long does it take to see results with weight loss medication?
Most people see initial weight loss within 4 weeks of starting. Meaningful weight loss (5–10% of body weight) usually occurs within 8–12 weeks. Maximum results are typically reached around 52–68 weeks. Weight loss medication works best alongside diet and exercise changes.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with doses up to 15 mg weekly. Wegovy (semaglutide) is a GLP-1-only agonist with doses up to 2.4 mg weekly. Clinical trials suggest Mounjaro may produce slightly higher average weight loss (15–21% vs 15%), but individual results vary. Both are once-weekly injections.
Can I track my weight loss progress using tools on MyWeightCheck?
Yes. Use our free BMI calculator to check your starting BMI and set a target healthy weight range. Our progress tracker lets you log your weight weekly and visualise your graph over time. Our GLP-1 weight loss calculator can help estimate potential results at different medication doses.
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.