“I track myself, therefore I am” is perhaps the most fitting way to describe the basic idea behind the Quantified Self movement which has gained popularity all over the world in recent years. Increasingly, people have started to record and measure their own body-related data, tracking changes over time in metrics such as body weight, blood pressure, caloric expenditure, and the ever-present Body-Mass-Index (BMI). Simultaneously, the sale corresponding apps, sensors, smartwatches, and weighing scales that provide the technical means to collect this data has experienced a continuing surge. The sensors on Nike+ devices, for example, track movement, distance, and speed during physical activities such as running. Apparently, people love collecting these data, fueled by the promise of becoming slimmer and improving their health, physical fitness and appearance. Many of them are inspired specifically by the desire to lower their BMI. Since 1997, when the World Health Organization (WHO) declared a “global obesity epidemic,” overweight and obesity have been treated as serious public health problems. A BMI of over 25 for two-thirds of Americans as well as for half of Europeans is now seen as the worrying reality we face and an impending disaster we must fight to avert. It is only consistent that numerous studies have explored the “hefty” role of the BMI as the most important indicator of body fatness and predictor of morbidity and mortality. In Germany, the discussion about the right body weight has intensified from 2004 on, spiking in 2007 due to the AGENDA 2010 policy that introduced the concept of (financial) patient responsibility and focused on reducing health costs through disciplined patients who are more health-conscious.

Self-Tracking at Home – Part of the Daily Routine.
Photo: D. Frommeld

Using the BMI, the idea of the “fat German body” was brought into general health discourse. In the same year, the former Minister for Consumer Protection, Renate Künast, spoke about “why the Germans are becoming fatter and what we should do against it” in her official government report and book, “Die Dickmacher” (“Fatteners”). Here, a BMI over 25 was named as an indicator for obesity, obesity declared a rampant problem, and the “War on Fat” introduced to Germany. When searching for conceptions of the normal or ideal body, it is immediately apparent that BMI metrics have become the obligatory standard. Media reports about individuals and groups being “too fat” have become a constant in public life and a value of over 25 becomes an instant and permanent reason for dieting. Self-disciplinary techniques such as dieting and fitness programs, surgical methods like liposuction or stomach stapling, a body-oriented tendency to care/worry about oneself, and a corresponding methodical lifestyle represent a body discourse in which the normal or ideal body weight is defined by a specific range (BMI between 18.5 and 24.9).

To fully understand this mounting obsession with body fat, it is necessary to investigate how knowledge of the body is produced, what parts various actors play in this process, and who or what is responsible for the creation of certain beliefs as to what should be considered normal, healthy, beautiful, or not. Based on an analysis of selected historical European and US-American documents (medical and statistical textbooks and articles), self-help-books and advertisement, I claim that our definition of obesity is a biopolitical, global construction with a long historical background. I concentrate on the late 19^th century and early 20^th century to show that our prevailing understanding of overweight, obesity and health, in connection with the BMI, relies on “technologies of power” (Foucault) that were planned to rule people and populations. During a period of mechanization, scientification, and professionalization, these “technologies of power” started as political efforts of measuring soldiers in institutions with the intent of creating standardized bodies for the emerging institutional machinery in modern society. Statistics, medicine, and politics provide the historical context whose intricate interconnections lead to the current understanding of the BMI. Comparing these discourses and practices with those after 1960 shows, firstly, that certain boundary definitions have been incredibly resilient and have survived until present day times. Secondly, the historical analysis of statistical, medical and cultural discourses leads to the conclusion that a very specific perception has developed as to what is to be considered right and good for the body. The protection against abnormality (e.g., surplus weight) and the medicalization of obesity has been the logical consequence and is practiced until today. For example, in Germany, BMI metrics decide whether people are granted full civil-servant status or not; if they have a BMI of over 25 (which stands for overweight and obesity) they are rejected. For ten years, the BMI has been increasingly criticized and other measures to determine obesity (and the related comorbidities and health care costs) have been recommended. Beyond that, others are maintaining that there is no real alternative to the BMI.

BMI categories such as underweight, normal weight, and overweight classify people and seem to lead to three different body identities. Two effects become apparent through this analysis: the conveyed body knowledge seems to influence nutritional habits, lifestyle and body perception. Among other things, this knowledge promises health, good fortune, success, and a measure of security. This may explain why the BMI has become such a strong and popular instrument and why it is used everywhere we talk about food, fatness, and fitness. Measuring it and tracking anything that may affect it, to the extent of voluntarily placing one’s own body under permanent surveillance, is the conclusion that many appear to be reaching in order to protect their identities from the constant threat of being reclassified. On the tightrope of BMI, the balancing-pole of self-tracking apps and devices may be the only way to keep from falling off and being cast aside.