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
Foods That Stimulate Weight Loss — and Prescription Options in the UK
While certain foods like high-protein options, fibre-rich vegetables, and whole grains can support weight loss efforts, the reality is that diet alone isn't always enough for sustainable results. For adults struggling with weight management in the UK, prescription weight loss medications are now available through both NHS and private routes. Combined with dietary changes and increased physical activity, these prescription options may help achieve more significant results. Our free GLP-1 weight loss calculator can help you understand potential outcomes with medication-supported weight management.
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've been trying dietary changes without sufficient results, prescription weight loss medications offer a clinically proven alternative. The UK has three main GLP-1 receptor agonist medications licensed for weight management:
- Mounjaro (tirzepatide) — dual GIP/GLP-1 agonist, once-weekly injection, average weight loss 15–21% in clinical trials
- Wegovy (semaglutide) — GLP-1 agonist, once-weekly injection, average weight loss around 15% in trials
- Saxenda (liraglutide) — GLP-1 agonist, daily injection option
These are prescription-only medicines that work by reducing appetite, helping you feel fuller sooner, and supporting better food choices. Eligibility requires a BMI of 30 or above, or 27+ with weight-related health conditions like type 2 diabetes or high blood pressure. Individual results vary, and medications work best alongside reduced-calorie diet and physical activity. Our BMI calculator can help you check your current BMI and understand your eligibility.
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 route: Referral through your GP to a tier 3 specialist weight management service. Access varies significantly by region and waiting times can be lengthy in many areas.
Private route: Online consultation with a UK-licensed prescriber through registered pharmacies. Available without NHS referral, typically faster access, costs range from approximately £130–£320 monthly depending on dose.
Start by speaking with your GP about weight management options in your area. They can assess whether prescription medication is appropriate for you, discuss NHS availability, or advise on private options. Your GP can also review your BMI, health history, and any weight-related conditions to determine eligibility. Even if NHS services have long waiting times, private access may be available while you wait.
- 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 foods alone help me lose weight without medication?
Yes, certain foods support weight loss — high-protein options, fibre-rich vegetables, whole grains, and foods with low calorie density all help. However, for many people, dietary changes alone provide modest results. If you have a BMI over 30 or weight-related health conditions, prescription medication combined with diet and exercise may be more effective. Use our GLP-1 weight loss calculator to explore potential outcomes with medication support.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with average weight loss around 15–21%, while Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both are once-weekly injections. Mounjaro has a different mechanism, potentially offering greater appetite suppression. Individual response varies. Your prescriber can advise which is suitable for you.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility generally requires BMI 30 or above, or BMI 27–29.9 with weight-related conditions (type 2 diabetes, high blood pressure, heart disease). South Asian, Black African, and Black Caribbean adults may qualify at lower BMI thresholds. Availability depends on your local integrated care board. Speak to your GP about referral to specialist weight management services in your area.
How much does private prescription weight loss medication cost in the UK?
Private GLP-1 medications typically cost £130–£320 per month depending on dose. Mounjaro and Wegovy are most commonly available. Costs vary between providers and may include prescriber consultation fees. Many people find private access faster than NHS waiting lists, though NHS services are free if you qualify and can access them.
Do weight loss injections work better than diet and exercise alone?
Clinical trials show prescription GLP-1 medications produce greater average weight loss than diet and exercise alone — around 15–21% body weight versus 2–3% with lifestyle changes only. However, medications work best alongside dietary changes and physical activity, not instead of them. Your GP or prescriber can advise whether medication is appropriate for your situation and health goals.
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.