The mathematical formatting of obesity in public health discourse

Rising rates of obesity are of widespread public concern and are targeted by public health policies around the world. In this chapter, we examine the origins of the most common definition of obesity, which is based on the Body Mass Index (BMI). We draw on Skovsmose’s concept of formatting, combined with an examination of the origins of the BMI, to show how obesity is a form of realised abstraction. In particular, we show how, while the BMI originated as a statistical descriptor of specific populations, it is now used as a prescriptive construct applied to all individuals across the general population. We discuss how mathematics is therefore used to format or define obesity in a particular way, indicate some of the consequences of the particular way that this occurs through the BMI, and suggest some possibilities for mathematics teaching arising from this work. Our analysis is an example of how critical mathematics education provides a productive perspective with which to examine topics of widespread social concern, and thus inform both public education and mathematics education in schools.