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
What Does Overweight Mean?
Being overweight means having excess body weight that may increase health risks. In the UK, adults with a BMI between 25.0 and 29.9 are classified as overweight according to NHS guidance. However, being overweight doesn't automatically mean you're unhealthy — individual health depends on many factors including fitness level, diet, and overall lifestyle. Understanding whether you're overweight and what it means for your health is an important first step towards informed health decisions.
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.
NHS Definition and BMI Categories
The NHS classifies adults as overweight when their BMI falls between 25.0 and 29.9. BMI (body mass index) is calculated by dividing weight in kilograms by height in metres squared. For example, an adult who is 1.73m tall and weighs 75kg would have a BMI of approximately 25.1, falling into the overweight category.
It's important to note that BMI has limitations — it doesn't distinguish between muscle and fat, so athletes or very muscular individuals may have a high BMI but low body fat. Additionally, waist circumference is also important: men over 94cm (37 inches) and women over 80cm (31.5 inches) have increased health risk, even at lower BMI levels. Use our free BMI calculator above to check your personal BMI and see where you fall on the NHS scale.
- BMI 18.5–24.9 = healthy weight
- BMI 25.0–29.9 = overweight
- BMI 30.0+ = obese
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.
Health Risks and Weight Management Options
Being overweight increases risk of type 2 diabetes, high blood pressure, cardiovascular disease, and certain cancers. However, even a 5–10% reduction in body weight can significantly improve health outcomes, including better blood sugar control and lower blood pressure. Weight management in the UK follows the NHS pathway: tier 1 support includes digital tools and self-help resources, tier 2 involves GP-based behaviour change programmes, and tier 3 specialist services may include prescription weight management medication for eligible adults. The NHS recommends losing weight at a rate of 0.5–1kg per week through a combination of dietary changes and increased physical activity. Track your progress using our free progress tracker and convert measurements between kg, stone, and pounds with our weight converter.
- 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's the difference between overweight and obese?
According to NHS guidelines, overweight is a BMI of 25.0–29.9, while obese starts at BMI 30.0 and above. Both increase health risks, but obesity carries higher risk. Individual health also depends on fitness, diet, and other factors — not just BMI alone.
Can you be overweight and still healthy?
Yes. Health is multifactorial. Some overweight individuals have good fitness, normal blood pressure, and healthy blood sugar levels. However, excess weight does statistically increase risk of certain conditions, so discussing your personal health with your GP is valuable.
How can I check if I'm overweight?
Calculate your BMI using your weight and height — use our free BMI calculator on this page. The NHS defines overweight as BMI 25.0–29.9. You can also measure your waist circumference: increased risk begins at 94cm for men and 80cm for women.
What are the health risks of being overweight?
Overweight increases risk of type 2 diabetes, high blood pressure, heart disease, stroke, sleep apnoea, and certain cancers. However, modest weight loss (5–10%) can reduce these risks significantly and improve overall health outcomes.
What weight loss options are available on the NHS?
NHS support starts with tier 1 self-help and digital tools, progresses to tier 2 GP-based programmes, and tier 3 specialist services may offer prescription weight management medication. Eligibility for medication depends on BMI and health conditions — speak to your GP about what's available in your area.
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.