BMI
March 2026
What Does Your BMI Score Actually Mean? A Practical Healthy Weight Guide for Adults
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Open the Free BMI Calculator →What is BMI?
Body Mass Index = Weight (kg) ÷ Height² (m²). Developed in the 1830s as a population-level measure, adopted by the WHO in 1995. Widely used but with important limitations for individuals.
Breaking Down Every Category
| BMI | Category | Key Health Notes |
|---|---|---|
| Below 18.5 | Underweight | Risk of nutritional deficiencies, weakened immune function |
| 18.5–24.9 | Normal weight | Lowest all-cause mortality in most studies |
| 25–29.9 | Overweight | Elevated diabetes, hypertension, and joint pain risk |
| 30–34.9 | Obese Class I | Cardiovascular disease risk roughly doubles |
| 35+ | Obese Class II–III | Substantially shortened life expectancy without intervention |
5 Important Limitations of BMI
- Muscle vs fat — A bodybuilder may have BMI 30+ with very low body fat
- Ethnic differences — Asian adults face metabolic risks at lower BMI (threshold ~23)
- Age and sex — Women naturally carry higher body fat at the same BMI as men
- Fat distribution — Waist circumference (over 88 cm women / 102 cm men) matters more
- Pregnancy and illness — BMI is unreliable during pregnancy or after significant muscle loss
Practical Steps Toward a Healthier Weight
- A 500 kcal/day deficit produces ~0.5 kg/week weight loss — safe and sustainable
- 1.2–1.6 g protein per kg of bodyweight per day preserves muscle during weight loss
- Strength training improves insulin sensitivity even without weight loss
- Sleep 7–9 hours — poor sleep elevates hunger hormones by 15–20%
Frequently Asked Questions
Does BMI matter if I exercise regularly?
Physical fitness is a stronger predictor of cardiovascular health than BMI alone. A fit person at BMI 27 may have lower heart disease risk than a sedentary person at BMI 22.
Can children use this calculator?
No — children require age- and sex-specific BMI percentile charts. A paediatrician should evaluate children's weight status.
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