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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Simple Weight Loss Apps and Prescription Weight Loss Options in the UK
Weight loss apps can be useful tools for tracking progress and building healthy habits, but if you're looking for more support, prescription weight loss medication is now available to eligible UK adults. This guide covers simple weight management apps alongside prescription options like Mounjaro and Wegovy, how to access them through the NHS or privately, and whether you might be eligible. We'll help you understand all your weight management options so you can make an informed decision with your GP.
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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
If you're interested in weight management uk support beyond simple apps, three prescription-only medications are licensed in the UK for weight loss:
- Mounjaro (tirzepatide) — a once-weekly injection that activates dual GIP and GLP-1 pathways. Clinical trials showed 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 injection. The STEP-1 trial demonstrated average weight loss of approximately 15% body weight at the highest dose.
- Saxenda (liraglutide) — a daily GLP-1 injection, less commonly prescribed than Mounjaro and Wegovy but still available.
All three are prescription-only and require a clinical assessment before being prescribed. Individual results vary significantly, and these medications work best alongside dietary changes and physical activity, not instead of them. You can use our free GLP-1 weight loss calculator to estimate 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.
NHS vs Private Access — How to Get Started
NHS access: Weight loss medication is available through specialist tier 3 weight management services. You'll need a GP referral, and availability varies significantly by region. Waiting lists can be long in many areas, but if you're eligible, the NHS covers the full cost.
Private access: You can arrange a private online consultation with a UK-licensed prescriber without an NHS referral. If clinically appropriate, you'll receive a prescription that a GPhC-registered pharmacy can dispense. Costs range from approximately £129–£320 per month depending on the medication and dose.
Who is eligible: Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, hypertension, sleep apnoea, cardiovascular disease). Use our free BMI calculator to check your current BMI and see where you stand.
- 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 weight loss apps enough on their own?
Simple weight loss apps are helpful for tracking calories, logging meals, and monitoring progress. However, they don't address appetite regulation or metabolism. If you have significant weight to lose or related health conditions, prescription weight loss medication combined with an app may be more effective than either approach alone.
How do I find out if I'm eligible for prescription weight loss medication?
First, calculate your BMI using our free BMI calculator on this page. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions, you may be eligible. Book a GP appointment to discuss your options, or contact a private prescriber for a confidential online assessment.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) activates dual GIP and GLP-1 pathways and achieved higher average weight loss (15–21%) in clinical trials. Wegovy (semaglutide) activates GLP-1 only and achieved approximately 15% average weight loss. Both are once-weekly injections. The choice depends on individual health factors and prescriber recommendation.
Can I use a weight loss app alongside prescription medication?
Yes, absolutely. Many people use apps to track meals, water intake, and exercise while taking Mounjaro or Wegovy. This combination can reinforce good habits and help you see progress more clearly. You can track your weight loss journey with our free progress tracker alongside any medication you're prescribed.
How long do I need to take prescription weight loss medication?
This varies by individual and prescriber guidance. Some people use it for a defined period to reach a target weight, then stop. Others continue longer-term for weight maintenance, especially if they have obesity-related health conditions. Your prescriber will discuss the best approach for you during assessment and regular reviews.
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.