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
Free Weight Loss Tracker Printable for UK Adults
A weight loss tracker helps you monitor progress towards your health goals, especially when combined with prescription weight management options available in the UK. Whether you're using lifestyle changes, NHS weight loss programmes, or considering medication like Mounjaro or Wegovy, tracking your weight regularly is an evidence-based way to stay motivated and spot trends. This guide covers UK-licensed prescription weight loss medication options, eligibility criteria, and how to track your progress effectively alongside your GP's support.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Prescription Weight Loss Medication Options
Three prescription-only medications are licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a once-weekly GIP and GLP-1 receptor agonist injection. In clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 receptor agonist injection. Clinical data showed average weight loss of approximately 15% of body weight at 68 weeks.
- Saxenda (liraglutide) — a daily GLP-1 injection. Slightly lower average weight loss than weekly options, but still evidence-based for eligible adults.
All three are prescription-only and require a clinical assessment before being prescribed. Individual results vary significantly. These medications are typically used alongside lifestyle changes — diet and physical activity improvements remain essential for sustainable weight management and overall health benefits.
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 Eligibility in the UK
NHS access: Available through tier 3 specialist weight management services following a GP referral. NICE has approved tirzepatide and semaglutide for use within NHS services, though regional availability varies and waiting lists can be lengthy. Private access: Available through GPhC-registered online pharmacies following a licensed prescriber assessment, without requiring NHS referral.
Eligibility: You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds due to higher health risks at lower weights. Speaking with your GP about weight management options is the essential first step to understanding what's available to you personally.
- 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 should I include in a weight loss tracker?
Track your current weight (use our free weight converter to switch between kg, stone, and lbs), date, any medications you're taking, diet notes, activity level, and how you're feeling. Regular weekly weigh-ins (same day, same time) provide the clearest trend data. Our free progress tracker on this page makes this simple.
Can I get prescription weight loss medication on the NHS?
Yes, if you're eligible. You'll need to speak with your GP about referral to a specialist tier 3 weight management service. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions. NHS availability varies significantly by region, and waiting times can be several months.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro may have slightly higher average weight loss (15–21%) compared to Wegovy (approximately 15%), but individual results vary significantly. Both are once-weekly injections.
How quickly can I expect to see weight loss results?
The NHS recommends a sustainable weight loss rate of 0.5–1 kg per week. With prescription medications, clinical trials showed average losses over 12–18 months, not weeks. Results vary by individual, dose, and adherence to dietary and activity changes. Your GP can give personalised timeline guidance.
Do I need to diet and exercise while taking weight loss medication?
Yes. Clinical trials for all prescription weight loss medications showed results were achieved alongside a reduced-calorie diet and increased physical activity. Medication supports appetite regulation and blood sugar control, but lifestyle changes remain essential for sustainable results and overall health benefits.
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.