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
Benefits of Weight Loss for Your Health
Losing excess weight brings significant health improvements, even at modest levels. Research shows that shedding just 5–10% of your body weight can reduce blood pressure, improve blood sugar control, and lower your risk of serious health conditions. For many UK adults, weight management may involve lifestyle changes, and prescription weight loss medication is now available through the NHS and private services for those who meet eligibility criteria.
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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.
Key Health Benefits of Weight Loss
Losing weight delivers measurable health improvements across multiple body systems. Evidence shows that weight reduction helps lower blood pressure and cholesterol levels, reducing strain on your heart and blood vessels. Better blood sugar control follows weight loss, significantly lowering type 2 diabetes risk — a condition affecting millions of UK adults. Joint pain and osteoarthritis symptoms often improve as pressure on joints decreases, boosting mobility and physical activity capacity. Sleep quality typically improves as sleep apnoea severity reduces. Cancer risk also decreases, as excess weight is linked to 13 types of cancer. Beyond physical health, weight loss frequently improves mood, energy levels, and self-confidence, supporting overall wellbeing.
- Reduced cardiovascular disease risk
- Better blood sugar and HbA1c levels
- Lower blood pressure
- Decreased joint pain and improved mobility
- Reduced sleep apnoea symptoms
- Lower cancer risk
- Improved mental health and confidence
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.
Weight Loss Medication Options Available in the UK
For eligible UK adults, prescription weight loss medications are now available to support weight management alongside diet and exercise. Three options are licensed for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These GLP-1 weight loss injections help reduce appetite and support feeling fuller after smaller meals. You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Try our free GLP-1 weight loss calculator to see projected results at different doses. Access is available through NHS specialist weight management services or private prescribing following clinical assessment.
- Eligibility based on BMI and health status
- Once-weekly injections (Mounjaro and Wegovy) or daily (Saxenda)
- Used alongside reduced-calorie diet and physical activity
- Individual results vary — assess suitability with your prescriber
- 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.
How much weight do you need to lose to see health benefits?
Even losing 5–10% of your body weight brings measurable improvements. For a person weighing 100kg, this means 5–10kg loss. Use our free BMI calculator to establish your current status and target healthy weight range. Your GP can advise on realistic goals for your circumstances.
What is the fastest safe rate of weight loss?
The NHS recommends losing no more than 0.5–1 kg per week for sustainable results. This pace preserves muscle mass and is more likely to result in lasting change. Very gradual weight management (over 1.5 kg weekly) should only be pursued under medical supervision and may increase nutrient deficiency risk.
Can you lose weight without medication?
Yes. Most people can lose weight through calorie deficit, dietary changes, and increased physical activity. A 500 kcal daily deficit typically results in 0.5 kg weekly loss. However, medication may help if lifestyle changes alone haven't worked, or if you have significant obesity-related health conditions.
How do I find out if I'm eligible for NHS weight loss medication?
Speak to your GP about referral to a specialist tier 3 weight management service. Eligibility typically requires BMI of 30 or above, or 27–29.9 with weight-related conditions. NHS availability varies by region, and waiting times can be lengthy. Private options are also available following online clinical assessment.
Is weight loss medication safe for long-term use?
Licensed weight loss medications have undergone rigorous clinical trials and are considered safe for ongoing use in eligible adults. However, they require monitoring by a healthcare professional. Side effects are usually mild and temporary. Your prescriber will review suitability regularly and discuss any concerns with you.
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.