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
Weight Loss Tracker Apps and UK Prescription Medication
A weight loss tracker app can help monitor your progress, but combining tracking with prescription medication may offer more effective results for eligible UK adults. If you're managing your weight through medication like Mounjaro or Wegovy, a tracking app records your journey alongside clinical support. This guide explains UK-licensed weight loss medication options, who qualifies, and how prescription treatment works within the NHS and private healthcare systems.
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 Options
Three prescription-only weight loss medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide), a GLP-1 agonist given once weekly; and Saxenda (liraglutide), a GLP-1 agonist given daily. In clinical trials, Mounjaro demonstrated average weight loss of 15–21% of body weight, whilst Wegovy showed approximately 15% average weight loss — though individual results vary significantly. Eligibility for prescription weight loss medication typically includes adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds due to higher health risks at these levels. A prescriber will assess whether medication is suitable for you based on your individual health profile and medical history. Weight loss medications are most effective when used alongside reduced-calorie diet and increased physical activity — a tracker app can help monitor both medication response and lifestyle changes throughout your journey.
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.
Accessing Weight Loss Medication: NHS vs Private
NHS access to prescription weight loss treatment is through tier 3 specialist weight management services, typically requiring a GP referral. However, NHS availability and waiting times vary significantly by region — some areas have long waiting lists, whilst others may have limited access. Private access is available through GPhC-registered online pharmacies following an online clinical assessment by a UK-licensed prescriber; this route does not require NHS referral and offers faster access but involves private costs.
- Ask your GP about weight loss medications and local NHS specialist services
- Request a referral to tier 3 weight management if eligible
- Use our free BMI calculator above to check your personal BMI and discuss results with your GP
- If pursuing private treatment, ensure the prescriber is UK-licensed and the pharmacy is GPhC-registered
Whichever route you choose, tracking your weight with an app helps monitor progress and supports conversations with your prescriber about dose adjustments or continued treatment.
- 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 a weight loss tracker app with prescription medication?
Yes — tracking apps are helpful alongside prescription weight loss medication. Apps let you log weight, meals, and symptoms, providing data to share with your prescriber. Many people find combining tracking with medication like Mounjaro or Wegovy improves adherence and helps identify patterns. Always use tracking as a support tool, not as a replacement for clinical guidance.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist showing average weight loss of 15–21%, whilst Wegovy (semaglutide) is a GLP-1 agonist showing approximately 15% average weight loss. Both are once-weekly injections. Clinical trial results vary between individuals. Your prescriber will determine which medication suits your health profile. Our GLP-1 weight loss calculator can help estimate potential outcomes at different doses.
How do I check if I'm eligible for prescription weight loss medication in the UK?
You typically qualify if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at BMI 27.5 or above. Use our free BMI calculator to check your starting point, then discuss eligibility with your GP or a licensed prescriber.
What's the difference between NHS and private weight loss medication?
NHS treatment is through specialist tier 3 services (referral required, often involves waiting lists) but is free at point of use. Private treatment through online prescribers is faster and doesn't require NHS referral but involves private costs, typically £129–£320 monthly depending on dose and provider. Both routes require a clinical assessment and prescription from a licensed UK healthcare professional.
Can a weight loss tracker app replace prescription medication?
No. A tracking app is a useful monitoring and accountability tool but cannot replace medication if you're eligible for prescription treatment. Apps help you log progress, identify patterns, and support conversations with your prescriber — but medication like Mounjaro or Wegovy works through biological mechanisms that an app cannot replicate. Use both together for best results.
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.