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 App For Weight Loss Free in the UK
If you're searching for the best free weight loss app, you'll find plenty of calorie trackers and fitness tools online. However, if you're struggling with weight management, it's worth understanding that prescription weight loss medication is also available in the UK for eligible adults. This guide covers both free digital tools and evidence-based medication options — including how to access them through the NHS or private prescribers. Whether you need a weight loss app or want to explore GLP-1 medication, your GP can help assess what's right for you.
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.
Prescription Weight Loss Options Available in the UK
For eligible adults, prescription weight loss medications are now available in the UK alongside traditional apps and lifestyle changes. Three medications are currently licensed for weight management:
- Mounjaro (tirzepatide) — dual GIP and GLP-1 receptor agonist, once-weekly injection. Clinical trials showed average weight loss of 15–21% of body weight at maximum dose.
- Wegovy (semaglutide) — GLP-1 receptor agonist, once-weekly injection. Average weight loss approximately 15% body weight in clinical trials.
- Saxenda (liraglutide) — GLP-1 receptor agonist, daily injection. Available in the UK for weight management.
These are prescription-only medicines requiring clinical assessment. You cannot buy them without a prescription. Individual results vary significantly, and they work best alongside a reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses.
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.
How to Access Weight Loss Medication in the UK
NHS access: Referral to a tier 3 specialist weight management service is required. Ask your GP whether you're eligible and can be referred. Availability and waiting times vary significantly by region (ICB).
Private access: Online consultation with a UK-licensed prescriber followed by prescription from a GPhC-registered pharmacy. No NHS referral needed, though eligibility criteria remain the same (BMI ≥30, or BMI ≥27 with weight-related health conditions).
Everyone should start with their GP to discuss weight loss options. Free tools like our BMI calculator and weight converter can help you understand your current health metrics before that conversation.
- 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 there really good free weight loss apps available?
Yes. Apps like MyFitnessPal, Cronometer, Lose It!, and the NHS Weight Loss Plan app are free or have free versions. They track calories, nutrients, and progress. However, apps alone typically produce modest weight loss without lifestyle changes. For weight management uk, combining an app with diet and exercise gives better results than any single tool.
What does "eligible" mean for prescription weight loss medication?
You're eligible if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 with a weight-related health condition (type 2 diabetes, high blood pressure, heart disease, sleep apnoea, or high cholesterol). South Asian, Chinese, Black African, or Black Caribbean adults have lower thresholds (BMI ≥27.5). Your prescriber assesses eligibility individually.
Can I get GLP-1 weight loss medication on the NHS?
Yes, tirzepatide (Mounjaro) is approved for NHS specialist services. However, NHS access is through tier 3 weight management services, not standard GP prescription. Referral and waiting times vary by region. Private prescribing is faster but costs between £129–£320 monthly depending on dose.
How do I know if weight loss medication is right for me?
Talk to your GP. They'll assess your BMI, health conditions, medications, and weight loss history. A clinical prescriber will evaluate whether GLP-1 medication is appropriate. These medications are tools, not replacements for diet and exercise. Use our BMI calculator to check your starting point before your GP conversation.
What's the difference between free apps and prescription medication for weight management?
Apps provide tracking, accountability, and behavioural support but rely entirely on user discipline. Prescription GLP-1 medication actively reduces appetite and supports feeling fuller, making calorie restriction easier. Combining both — a free weight loss app plus prescription medication plus lifestyle changes — gives the best evidence-based results for eligible adults.
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.