World Health Organization classification of overweight and obesity (BMI = weight(kg)/height(m)2
| Class | BMI (kg/m2) | Risk of comorbidity |
|---|---|---|
| Based on World Health Organization. Obesity: preventing and managing the global epidemic. Geneva: WHO, 1997. | ||
| Underweight | <18.5 | Low |
| Normal range | 18.5–24.9 | Average |
| Overweight (grade 1 obesity) | 25.0–29.9 | Mild increase |
| Obese (grade 2 obesity) | 30.0–39.9 | Moderate/severe |
| Morbid/severe obesity (grade 3) | ≥40.0 | Very severe |