After years of controversy, the American Medical Association no longer recommends BMI (Body Mass Index) as a measure of weight and health.
The Body Mass Index (BMI) is a measurement we use to assess a person’s body weight in relation to their height. Adolphe Quetelet, a Belgian mathematician and statistician who sought to establish a standardized method for evaluating obesity and malnutrition in populations, developed it in the mid-19th century. Quetelet was interested in studying the physical characteristics of individuals and how they related to various aspects of health. In 1832, he introduced the concept of the Body Mass Index, which he initially referred to as the Quetelet Index. Quetelet’s intention was to create a simple yet effective formula that could provide a numerical value indicating the degree of obesity or thinness in a person.
The formula for calculating BMI is relatively straightforward. It involves dividing an individual’s weight (in kilograms) by the square of their height (in meters). The resulting value represents the BMI, which is often expressed in units of kg/m². By comparing an individual’s BMI to a range of predefined categories, such as underweight, normal weight, overweight, and obese, it is possible to assess their weight status and potential health risks associated with it.
Initially, researchers and healthcare professionals primarily used BMI as a population-level measurement for assessing patterns of obesity and malnutrition within a society. Over time, it gained popularity as a simple and cost-effective tool for assessing an individual’s weight status in clinical settings.
The widespread use of BMI began in the late 20th century when the World Health Organization (WHO) and other international health organizations adopted it as a standard measure for evaluating body weight and obesity on a global scale. The simplicity of the BMI calculation, along with its reasonably accurate correlation with body fat percentage, contributed to its wide acceptance and integration into medical practice and public health initiatives.
Despite its widespread use, the BMI has been subject to criticism and limitations. Some argue that it fails to consider factors such as body composition, muscle mass, and distribution of fat, which can vary among individuals. It fails to account for the higher percentage of body fat in women’s bodies than men’s. Consequently, individuals with a higher muscle mass, such as athletes, may have a higher BMI despite being in good physical condition. Furthermore, the BMI does not differentiate between types of fat, such as visceral fat (located around organs) and subcutaneous fat (located under the skin), which can have different health implications.
Even though BMI itself is not racist, the way we use and interpret it in certain contexts can contribute to racial disparities and perpetuate biases if not applied appropriately or in conjunction with other relevant measures. Many studies over time have found that BMI is not a reliable marker to predict overweight in Asians particularly. According to a study conducted by Wageningen University, The Netherlands, Indians had a higher body fat percentage (%BF) even at a lower BMI. This was not true for other races like Caucasians. The study concluded that the relationship between %BF and BMI was ‘ethnic-specific.’
Despite these limitations, the BMI remains a commonly used tool in healthcare and public health due to its simplicity and practicality.