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
Understanding Your BMI Graph — NHS Health Categories
A BMI graph visually shows where your weight falls across the health spectrum using NHS-standard categories. Whether your BMI indicates a healthy weight, overweight, or obese range depends on your height and weight together. Understanding your position on the BMI scale helps you see your health context clearly. The NHS uses standardised BMI categories to assess weight-related health risk across the UK population. Use our free BMI calculator above to find your exact BMI and see where you sit on the graph instantly.
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 BMI Categories & What Your Range Means
The NHS defines five BMI categories for UK adults:
- Underweight: BMI below 18.5 — may indicate insufficient calorie intake or underlying health issues
- Healthy weight: BMI 18.5 to 24.9 — associated with lowest health risk
- Overweight: BMI 25.0 to 29.9 — increased risk of weight-related health conditions
- Obese (Class I): BMI 30.0 to 34.9 — significantly elevated health risk
- Obese (Class II): BMI 35.0 to 39.9 — high health risk
- Severely obese (Class III): BMI 40.0 and above — very high health risk
For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these groups face higher cardiovascular and diabetes risk at the same BMI. The healthy weight range for these populations is 18.5 to 22.9, and overweight begins at 23.0.
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 Weight Management & When to Seek Help
The NHS offers a structured four-tier weight management pathway. Tier 1 includes self-help tools, apps, and digital support — exactly like the free calculators on MyWeightCheck. Tier 2 involves your GP, who may refer you to local weight management programmes. Tier 3 offers specialist multidisciplinary services where prescription medications such as Mounjaro or Wegovy may be considered. Tier 4 is bariatric surgery for severe obesity with significant health complications.
Speak to your GP if your BMI graph shows you're in the overweight or obese ranges, especially if you have weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Your GP can discuss which NHS tier is appropriate for you and what support is available in your area.
- 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 accurate is a BMI graph for everyone?
BMI is a useful screening tool but has important limitations. It doesn't distinguish between muscle and fat — athletes may have a high BMI despite low body fat. BMI also doesn't account for where fat is stored, age, bone density, or pregnancy. Your GP can assess your individual health beyond BMI alone.
What's the difference between overweight and obese on the BMI graph?
Overweight (BMI 25–29.9) indicates moderate weight-related health risk, while obese (BMI 30+) indicates significantly higher risk of type 2 diabetes, cardiovascular disease, and certain cancers. The NHS treats these categories differently in terms of recommended interventions and monitoring.
Why does the NHS BMI graph have different ranges for some ethnicities?
Research shows that South Asian, Chinese, Black African, and Black Caribbean populations develop type 2 diabetes and heart disease at lower BMI levels than other groups. The NHS recommends adjusted thresholds (healthy BMI 18.5–22.9 for these populations) to better reflect true health risk.
Can I use a BMI graph to know if I need weight loss treatment?
A BMI graph gives you a starting point, but eligibility for prescription weight loss treatment requires a clinical assessment. Generally, the NHS considers medications for adults with BMI 30+ or BMI 27–29.9 with weight-related health conditions. Your GP will discuss whether you're suitable for any treatment.
How often should I check my BMI on a graph?
The NHS recommends checking your weight regularly — monthly or quarterly is typical for weight management. Use our free BMI calculator regularly to track your progress. However, weight naturally fluctuates day-to-day, so focus on longer-term trends rather than single measurements.
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.