Downsizing obesity: On Ancel Keys, the origins of BMI, and the neglect of excess weight as a health hazard in the United States from the 1950s to 1970s.

In 1972 Body Mass Index, BMI was put forth by physiologist Ancel Keys in his analysis of Seven Countries Study heart disease epidemiological data as the best available measure of obesity. This work culminated more than 20 years of effort by Keys to discredit the accepted measure of obesity, weight relative to height, along with a major public health campaign in the United States to fight heart disease through weight control. Here, I retrace his campaign to replace weight as a measure of obesity and analyze its methodology and relationship to the broader research field of heart disease epidemiology. I also explore why the epidemiological community accepted BMI despite Keys's failure to demonstrate that either it or adiposity (body fat content), were superior as predictors of heart disease-one of the Seven Countries Study's central aims.