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 Do BMI 35 and BMI 30 Mean in the UK?
BMI 35 and BMI 30 are both in the obese range according to NHS guidelines, but represent different levels of health risk. BMI 30 marks the start of obesity, whilst BMI 35 indicates a higher risk threshold. Understanding where you fall on the NHS BMI scale helps you and your GP identify the right health guidance and weight management support for your situation. Both categories qualify for prescription weight management options in the UK.
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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 Health Classifications for BMI 30 and BMI 35
BMI 30 is classified as Obese (Class I) under NHS guidelines. At this threshold, health risks including type 2 diabetes, cardiovascular disease, and high blood pressure begin to increase significantly. BMI 30 is the official starting point for obesity classification in the UK.
BMI 35 falls into Obese (Class II) and carries higher health risks than BMI 30. At this level, the NHS considers you at substantially increased risk for serious weight-related conditions including heart disease, stroke, and complications from diabetes.
Both categories qualify for weight management support in the UK. Adults with BMI 30 or above, or BMI 27–29.9 with weight-related health conditions, may be eligible for prescription weight loss treatment through NHS specialist services or private prescribing. Use our free BMI calculator to check your personal BMI and understand your category.
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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 Management Options for BMI 30 and BMI 35 in the UK
The NHS supports a stepped approach to weight management. For BMI 30–34.9, lifestyle changes including diet and physical activity are typically the first step, often through tier 1 or 2 NHS programmes. For BMI 35 and above, GPs may refer you to specialist tier 3 weight management services, where prescription options like Mounjaro (tirzepatide) or Wegovy (semaglutide) may be considered alongside lifestyle support.
Both categories benefit from tracking progress. Our free weight loss calculator can help you project realistic outcomes if considering GLP-1 medication, and our progress tracker lets you log weight changes over time. Always discuss your options with your GP first — they can assess which approach suits your individual health profile.
- 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 health risks are associated with BMI 30?
BMI 30 increases risk of type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea, and certain cancers. Losing even 5–10% of body weight can significantly reduce these risks and improve health markers like blood sugar and cholesterol levels.
What's the difference between BMI 30 and BMI 35?
Both are in the obese range, but BMI 35 represents higher health risk. BMI 30 is Class I obesity; BMI 35 is Class II. At BMI 35, health complications are more likely and progressed, making medical intervention more commonly recommended by the NHS.
Can I get prescription weight loss medication at BMI 30 in the UK?
Yes. Adults with BMI 30 or above qualify for assessment for prescription weight loss treatment like Mounjaro or Wegovy. Eligibility also includes BMI 27–29.9 with weight-related conditions. Your GP can refer you to NHS specialist services or you can seek a private clinical assessment.
How much weight would I need to lose to move from BMI 35 to BMI 30?
The amount varies by height and current weight. For a 5ft 8in adult at BMI 35 (approximately 94kg), losing around 10kg would bring you close to BMI 30. Use our weight converter and BMI calculator to find your specific target weight for your height.
Is BMI the only measure of health at these weights?
No. Whilst BMI is a useful screening tool, the NHS also considers waist circumference, blood pressure, blood sugar, cholesterol, and overall fitness. Your GP can assess your full health picture and recommend the most appropriate management plan for you personally.
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.