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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Best Weight Loss Apps Free — Including UK Prescription Options
Free weight loss apps can help you track progress and stay motivated, but for many UK adults with overweight or obesity, prescription medication may also be an option. While there are excellent free apps available, prescription weight loss treatments like Mounjaro and Wegovy have shown clinical evidence for supporting weight management alongside lifestyle changes. This guide covers both free digital tools and UK-licensed medication options to help you understand what's available. Use our free BMI calculator to check your starting point, and our GLP-1 weight loss calculator to explore what medication-based weight management might look like for your situation.
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
If you're looking for weight management support in the UK, prescription medications are available alongside free apps and lifestyle changes. The main UK-licensed options are:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection, once weekly, with clinical trials showing average weight loss of 15–21% of body weight
- Wegovy (semaglutide) — a GLP-1 injection, once weekly, with trial data showing average weight loss around 15% of body weight
- Saxenda (liraglutide) — a GLP-1 injection, once daily, offering another option for eligible adults
These are prescription-only medicines. Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Individual results vary significantly, and these medications work best alongside reduced-calorie diet and increased physical activity — not instead of lifestyle changes. A GP or licensed prescriber will assess whether prescription weight loss treatment is suitable for you based on your personal health profile.
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 in the UK
NHS access: Weight loss medication may be available through NHS specialist tier 3 weight management services if you're referred by your GP. However, availability varies significantly by region, and waiting lists can be lengthy — sometimes several months or longer depending on your local integrated care board.
Private access: Prescription weight loss treatment is also available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. This route is faster but involves a cost. Both routes require a proper prescription and clinical assessment — weight loss medication is never available without professional medical review.
Start by speaking with your GP about whether you might be eligible and what options are available in your area. Try our weight loss calculator to understand potential outcomes at different doses.
- 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.
Are free weight loss apps effective?
Free apps are useful for tracking calories, water intake, and exercise. They support behaviour change and motivation. However, they don't address underlying appetite regulation or metabolic factors. Combined with lifestyle changes, they're a solid foundation — but for some people, prescription medication alongside an app provides better results. The evidence suggests combining methods works best.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management. Mounjaro is a dual GIP and GLP-1 agonist (activates two hormone pathways), while Wegovy is a GLP-1 agonist only. Clinical trials showed Mounjaro users lost slightly more weight on average (15–21% vs 15%), but individual results vary. Both require prescription and clinical assessment.
How do I check if I'm eligible for prescription weight loss treatment?
Generally, you're eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions. Use our free BMI calculator to check your BMI first. Then speak with your GP about eligibility and options available through NHS services or whether private prescription might suit you. Your GP can give personalised advice based on your full health picture.
How much does prescription weight loss medication cost privately in the UK?
Private costs vary by dose and provider, typically ranging from approximately £129–£320 per month for Mounjaro or Wegovy. NHS access is free if available through your local service, though waiting lists vary. Costs depend on which dose you're on and how long you need treatment. A private prescriber can give you exact pricing.
Can I use a free weight loss app alongside prescription medication?
Yes, absolutely. Many people combine prescription medication with free tracking apps for best results. Apps help monitor calories, exercise, and progress — medication supports appetite regulation and metabolic changes. The combination of digital tracking tools, medication, and lifestyle changes typically gives the best outcomes. Our progress tracker can help you log your journey.
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.