Overweight and obesity can be measured in different ways

Overweight and obesity refer to the condition in which excess fat has accumulated in the body. This condition is a risk factor for a range of diseases and disorders. The extent of overweight is determined in various ways.

The most common method of determining weight status is Body Mass Index (BMI). This measure relates an individual’s weight to his or her height. According to the WHO classification, individuals with a BMI between 25 and 30 are defined as overweight and those with a BMI equal to or over 30 as obese (see Table 1).

Abdominal skinfold measures, Waist-to-Hip ratio (WHR) and waist circumference are considered to be markers of central obesity or intra-abdominal fat. Waist circumference in combination with BMI has shown to be the best descriptor of obesity and predictor of health risks. A waist size greater than 102 cm for men and 88 cm for women increases the risk for most weight-related illnesses.

Other methods for measuring body fat include using electronic impulses, water tank submersion, scanning techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) and special scales. These newer techniques, although providing more precise measures of body fat, are costly and impractical for use in large epidemiological studies or in population surveys (WHO, 2000d; Kuller, 1999).

In this EUphact, overweight and obesity are described in terms of BMI.

Table 1: Classification of Overweight and Obesity by BMI (WHO, 2000).

Limitations of BMI as a measure of overweight

BMI is considered to be the most appropriate measure of overweight and obesity prevalence on a population level. Read here about the Limitations of BMI as a measure of overweight and obesity.