There is a widely prevalent myth amongst the populace that normal body weight always equals healthy weight and they do not need to worry about practising healthy lifestyle behaviours. However, nothing could be further from the truth. Normal weight obesity is well recognised entity. In my post “What is obesity – is it merely about BMI?” What is obesity? obesity had been defined as “excessive body fat accumulation (not weighing too much), which is associated with clear risks to health.” Surprisingly, even though obesity has been defined as the presence of ‘excess’ fat, there is no consensus on how to define obesity based on body fat content or body fat percentage.
WHO has established Body Mass Index (BMI) as the parameter for identifying overweight and obesity. Because of its simplicity, it has become a popular tool for assessing the prevalence of obesity and overweight at the population level. However, BMI has some serious limitations which will be discussed in detail in a subsequent post. The main limitation of BMI is that it cannot differentiate body fat from lean (fat-free) mass and central (intra-abdominal fat or visceral fat; colloquially known as belly fat) from peripheral fat. As a result, current BMI criteria miss more than half of the individuals with increased body fat percentage, who would otherwise be categorised as ‘obese’ using the WHO criteria of excess body fat, especially in older adults.