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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Top Weight Loss Apps and Prescription Options in the UK
Weight loss apps can be helpful tools for tracking progress and building healthier habits, but for many people in the UK, prescription weight management medication may offer additional support. If you're looking to lose weight, understanding your full range of options—from digital apps to prescription treatments—is essential. This guide explores both approaches and helps you understand what's available on the NHS and privately, based on your individual circumstances and BMI.
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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 Management Options
If you have a BMI of 30 or above, or 25–29.9 with weight-related health conditions, prescription weight loss medication may be available to you in the UK. Three main options are currently licensed:
- Mounjaro (tirzepatide) — A once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. Clinical trials showed average weight loss of around 15–21% of body weight over 72 weeks.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. STEP trials demonstrated average weight loss of approximately 15% of body weight at 68 weeks.
- Saxenda (liraglutide) — A daily GLP-1 injection. A different injection frequency and dose schedule compared to Mounjaro and Wegovy.
All three are prescription-only medicines requiring a clinical assessment to establish suitability. Individual results vary significantly, and these medications work alongside dietary changes and increased physical activity, not instead of them. Our free GLP-1 weight loss calculator can help you explore potential weight loss projections at different doses.
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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.
How to Access Weight Loss Treatment in the UK
Access to prescription weight management differs between the NHS and private options. On the NHS, you'll typically be referred to a specialist tier 3 weight management service by your GP—though availability and waiting times vary significantly by region. Private access is available through UK-licensed prescribers following an online clinical assessment, without requiring an NHS referral.
Your first step is a conversation with your GP, who can assess whether you meet eligibility criteria and discuss whether prescription medication is appropriate for you. They can also advise on NHS weight management services in your area. Calculate your personal BMI using our free BMI calculator to understand where you currently sit, then discuss options with your healthcare provider based on your individual health profile and goals.
- 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 weight loss apps replace prescription medication?
Weight loss apps are useful for tracking habits and monitoring progress, but they work differently to prescription medication. Apps support behaviour change, while medications like Mounjaro and Wegovy help regulate appetite at a biological level. Many people use both together—apps for tracking, medication for additional support—alongside dietary changes. Your GP can advise what combination suits your situation.
Am I eligible for prescription weight loss medication on the NHS?
Typical NHS eligibility includes a BMI of 30 or above, or 25–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. However, eligibility varies by region and availability of specialist services. Speak to your GP for a personalised assessment and information about tier 3 weight management services in your area.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1-only agonist. In clinical trials, Mounjaro showed slightly higher average weight loss (15–21%) compared to Wegovy (around 15%), though individual results vary considerably. Both are once-weekly injections. Your prescriber will assess which is most appropriate for you.
How long do I need to take prescription weight loss medication?
Duration depends on your individual response and health goals. Many people continue treatment long-term to maintain weight loss, as weight often returns if medication is stopped. Your prescriber will monitor your progress and adjust your plan accordingly. Think of it as part of ongoing weight management, similar to how someone with diabetes manages blood sugar long-term.
Can I use weight loss apps and prescription medication together?
Yes, many people find this combination effective. Apps help track meals, exercise, and weight changes, while prescription medication supports appetite regulation. Together, they reinforce healthier habits and provide motivation. A progress tracker can help you log your weight loss journey alongside any medication you may be taking.
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.