What is Obesity
Overweight and obesity occur when excess fat accumulates in the human body, posing a risk to health. Current definitions are based on both the body mass index and the waist circumference. As height is important, the body mass index (BMI) is an indicator of fat storage independent of height. It is calculated as body weight divided by height squared. Waist circumference has more recently been included in efforts to classify obesity, as the distribution of body fat has been found to be important and carrying it around the abdomen has been found to be especially unhealthy. Abdominal obesity is classified as a waist circumference of more than 88 cm in women and more than 102 cm in men.
The World Health Organization (WHO) defines disease risk on the basis of both BMI and waist circumference (see Table). A gain in body weight or waist circumference is indicative of increasing health risk.
| Classification | BMI (KG/m²) | Waist Circumference | |
|---|---|---|---|
| Men ≤ 102cm | > 102cm | ||
| Women ≤ 88cm | > 88cm | ||
Underweight |
< 18.50 | * | * |
| Normal Range | 18.50 - 24.99 | Reference | + |
| Overweight | 25.00 - 29.99 | Increased | High |
| Obese | ≥ 30.00 | High | Very High |
*Underweight persons have lower risk of type2 diabetes, hypertension and cardiovascular diseases, but higher risk of other diseases and early mortality
+ Increased waist circumference can also be a marker for increased risk in persons with normal weight.
Source: WHO / NIH
