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 Makes a "Nice Body" in UK Health Terms?
The concept of a "nice body" varies widely between individuals, but from a UK health perspective, it's less about appearance and more about achieving a weight and body composition that supports your physical health and wellbeing. The NHS defines health primarily through metrics like BMI, waist circumference, and overall fitness rather than aesthetic ideals. A healthy body is one that allows you to live an active life, reduces your risk of weight-related health conditions, and makes you feel confident and capable. Understanding what healthy actually means—rather than chasing unrealistic standards—is the foundation of sustainable wellness.
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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.
UK Health Standards for Body Composition
The NHS emphasises that a "nice body" or healthy body is one within a healthy weight range for your height. According to NHS guidance, this means a BMI between 18.5 and 24.9 for most adults. However, BMI alone doesn't tell the complete story—body composition (the ratio of muscle to fat) matters too. Two people at the same weight can look completely different depending on their muscle mass.
Key measurements beyond BMI include:
- Waist circumference: Men over 94cm (37in) and women over 80cm (31.5in) face increased health risks, regardless of BMI
- Body fat percentage: Healthy ranges vary by age and sex—typically 18–24% for men and 25–31% for women
- Cardiovascular fitness: Regular physical activity is as important as weight itself
- Muscle tone and strength: Associated with better metabolic health and longevity
For South Asian, Chinese, Black African, or Black Caribbean adults, the NHS recommends lower BMI thresholds (18.5–22.9) due to higher cardiovascular risk at standard weights. Use our free BMI calculator to check where you fall on the UK health spectrum.
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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.
Achieving Sustainable Body Health in the UK
Rather than chasing a narrow aesthetic ideal, the NHS recommends focusing on sustainable lifestyle changes that support long-term health. This includes regular physical activity (150 minutes of moderate exercise per week), balanced nutrition, adequate sleep, and stress management. Weight loss, if needed, should be gradual—approximately 0.5 to 1kg per week—and combined with strength training to preserve muscle.
For those managing their weight through diet and exercise alone, progress tracking helps maintain motivation. Our free weight converter and progress tracker allow you to log your journey in whatever units feel natural to you—whether that's stone, pounds, or kilograms. If you're overweight (BMI 25–29.9) or obese (BMI 30+), speak with your GP about personalised support. Prescription weight loss medications are available for eligible adults, alongside lifestyle intervention. The goal is feeling strong, capable, and healthy—not conforming to a specific image.
- 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 a "nice body" and a healthy body?
A "nice body" is subjective and appearance-focused, while a healthy body is measured by metrics like BMI, waist circumference, cardiovascular fitness, and muscle strength. The NHS prioritises health over aesthetics. A healthy body reduces your risk of type 2 diabetes, heart disease, and certain cancers—regardless of how it looks.
Is BMI the only measure of a healthy body?
No. BMI is a useful screening tool but has limitations—it doesn't account for muscle mass or where fat is stored. Waist circumference, body fat percentage, fitness level, and overall lifestyle are equally important. Your GP can give you a complete health assessment.
How long does it take to achieve a healthier body composition?
Sustainable changes typically show results within 8–12 weeks, though body composition changes (gaining muscle, losing fat) may take longer than scale weight changes. Aim for 0.5–1kg of weight loss per week combined with strength training for best results.
Can I have a healthy body at different weights?
Yes. Two people at different weights can both be healthy if their BMI, waist circumference, fitness, and lifestyle are appropriate for their individual age, sex, and ethnic background. Health is personal and influenced by genetics, activity level, and overall wellbeing.
Where can I get personalised body health guidance in the UK?
Your GP is the best starting point. They can assess your BMI, waist measurement, and health history, then refer you to NHS weight management services if appropriate. Use our BMI calculator as a starting point to understand where you currently fall on UK health guidelines.
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.