Misconceptions in the Use of Body Mass Index

Organizations such as the World Health Organization, Centers for Disease Control and Prevention, and American Medical Association all recognize the limitations of using body mass index (BMI) to define obesity (BMI ≥ 30 kg/m2). However, BMI is commonly used for screening and is also used in clinical practice as a standalone measure to define “overweight” (BMI, 25-29.9 kg/m2) and “obesity” (BMI ≥ 30 kg/m2). This review describes the genesis of the use of BMI and its value in research and description of populations, while showing that when it is used for diagnosis at the individual level, it falls down at certain age, sex, and race/ethnic groups. A brief history of the BMI, from its inception to its current use in identifying “obesogenic” environments, is provided. Although BMI is currently used in screening, for clinical assessment and management, many other indices are more accurate and useful. This report summarizes the benefits of BMI, in monitoring the ongoing global obesity epidemic, and its limitations as a screening or diagnostic tool in clinical settings.