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
Easy Weight Loss — UK Prescription Medication Options
Weight loss doesn't have to be complicated. If you're struggling with your weight, prescription medication may help alongside diet and exercise. The UK has several licensed options including Mounjaro and Wegovy, available through both NHS specialist services and private prescribing. These medications work by helping regulate appetite and food cravings, making sustainable weight management more achievable. Check your BMI using our free BMI calculator to see if you might be eligible, and consider speaking to your GP about what weight management support is available for you.
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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 Weight Loss Medications Explained
Three main prescription weight loss options are licensed in the UK:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injection given once weekly. 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 GLP-1 receptor agonist injection also given once weekly. In clinical trials, participants achieved an average weight loss of approximately 15% of their body weight.
- Saxenda (liraglutide) — a GLP-1 injection given daily, with similar weight loss outcomes to Wegovy.
All three work by helping reduce appetite, supporting feelings of fullness, and slowing how quickly food leaves your stomach. Individual results vary significantly, and these medications work best alongside lifestyle changes. Our GLP-1 weight loss calculator can help you 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 Access vs Private Prescribing — How to Start
NHS route: Ask your GP for a referral to a specialist tier 3 weight management service if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. NHS availability varies by region, and waiting lists can be lengthy in some areas.
Private route: You can access prescription weight loss medication through UK-licensed prescribers online without an NHS referral. A clinical assessment determines your eligibility based on your BMI, medical history, and current medications. Private costs typically range from £129–£320 per month depending on dose. Track your progress with our free progress tracker once you start 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.
What makes weight loss medication easier than just dieting?
Prescription weight loss medications work on the brain's appetite control centres, reducing hunger and cravings naturally. This makes it psychologically easier to stick to a reduced-calorie diet and makes healthy eating choices feel less of a struggle. They're designed to work alongside, not instead of, lifestyle changes.
Am I eligible for weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 25–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your BMI, then discuss eligibility with your GP, who can refer you to specialist weight management services.
How quickly will I see weight loss results?
Weight loss typically begins within the first 4 weeks for most people, but results vary. The NHS recommends losing 0.5–1 kg per week for sustainable results. Clinical trials show most significant weight loss occurs between weeks 8 and 20 as medication doses are increased.
Can I stop taking weight loss medication once I've reached my goal weight?
Your prescriber will advise on the best approach for you. Some people maintain weight loss after stopping medication, whilst others regain weight. Ongoing lifestyle changes—regular physical activity, balanced diet, and stress management—are crucial for maintaining any weight loss achieved.
What's the difference between easy weight loss medication and crash dieting?
Crash diets severely restrict calories, often causing muscle loss, nutritional deficiencies, and rapid weight regain. Prescription medications support gradual, sustainable weight loss (typically 0.5–1 kg weekly) whilst preserving muscle and allowing normal nutrition. This is why they're considered a safer, easier, and more evidence-based approach.
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.