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 a BMI of 33 Mean?
A BMI of 33 falls into the obese (Class I) category according to NHS guidelines. This means your weight carries increased health risks compared to the healthy BMI range of 18.5 to 24.9. However, a BMI of 33 is not a diagnosis or judgement—it's a screening tool to help you understand your health status. Many people with a BMI of 33 can improve their health significantly through lifestyle changes, and some may benefit from support or treatment from their GP. Use our free BMI calculator above to verify your personal BMI and explore what this means for you specifically.
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.
BMI 33 and NHS Categories
According to NHS guidance, a BMI of 33 falls into the obese (Class I) category, which spans 30.0 to 34.9. This sits above the overweight threshold (25.0 to 29.9) and below severely obese (40.0+). The BMI formula used is simple: weight in kg divided by height in metres squared. Your individual risk also depends on where fat is stored—excess weight around the abdomen carries greater cardiovascular risk than fat stored elsewhere.
It's important to note that the BMI range is the same for all UK adults, though people of South Asian, Chinese, Black African, or Black Caribbean heritage face higher health risks at lower BMI levels. Your GP may discuss alternative thresholds if this applies to you. Use our weight converter and BMI calculator to understand your current position and healthy weight range for your height.
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.
BMI Limitations and What Else Matters
BMI has important limitations: it does not distinguish between muscle and fat, so athletes or very muscular individuals may have a high BMI despite low body fat. BMI also ignores where fat is stored—waist circumference is equally important. The NHS recommends measuring waist circumference: men should aim below 94cm (37 inches); women below 80cm (31.5 inches). If you're concerned about your weight or health, your GP can assess your individual situation, discuss any underlying conditions, and recommend appropriate support—which may include lifestyle advice, referral to NHS weight management services, or, if eligible, prescription weight loss medication.
- 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.
Is a BMI of 33 considered obese?
Yes. According to NHS guidelines, a BMI of 33 falls into the obese (Class I) category, which spans 30.0 to 34.9. This is above the healthy range (18.5 to 24.9) and carries increased health risks including type 2 diabetes, heart disease, and high blood pressure. However, BMI is a screening tool, not a diagnosis.
What health risks are associated with a BMI of 33?
A BMI of 33 increases your risk of type 2 diabetes, cardiovascular disease, high blood pressure, sleep apnoea, and certain cancers. However, even modest weight loss of 5 to 10 per cent can meaningfully reduce these risks. Your GP can discuss your individual health situation and recommend appropriate support.
What is the healthy weight range for my height if my BMI is 33?
Your healthy weight range depends on your height. Use our free BMI calculator above to enter your height and see your ideal weight range (BMI 18.5 to 24.9). For example, at 5ft 8in (1.73m), healthy weight is approximately 55 to 74kg. Your GP can also provide personalised guidance.
Can I lower my BMI from 33 to a healthy range?
Yes. The NHS recommends losing 0.5 to 1kg per week through a combination of calorie reduction and increased physical activity. At this rate, losing 10 per cent of your body weight takes several months. Your GP can refer you to weight management services, and if eligible, prescription support may be available.
What if I'm very muscular—could my BMI of 33 be misleading?
Yes. BMI does not account for muscle mass, so very muscular or athletic individuals may have a high BMI despite low body fat. Your GP can assess your body composition more accurately using waist circumference, fitness level, and health markers like blood pressure and cholesterol, rather than relying on BMI alone.
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.