A Different Obesity Timeline By FREAKONOMICS April 6 2010
The obesity epidemic is generally portrayed as a relatively recent phenomenon, but new research paints a different picture. John Komlos and Marek Brabec find (gated version here) that obesity rates actually began rising in the early 20th century, with significant upsurges after the two World Wars. The authors point out that “the ‘creeping’ nature of the epidemic, as well as its persistence, does suggest that its roots have been embedded deep in the social fabric and are nourished by a network of disparate sources…” Komlos and Brabec point to factors like the industrialization of food production, the spread of automobiles, the spread of the media, the IT revolution, and the growing culture of consumption in America to explain the trend.
The Trend of Mean BMI Values of US Adults, Birth Cohorts 1882-1986 Indicates that the Obesity Epidemic Began Earlier than Hitherto Thought
John Komlos, Marek Brabec
NBER Working Paper No. 15862* Issued in April 2010
The trend in the BMI values of the US population has not been estimated accurately because time series data are unavailable and because the focus has been on calculating period effects. In contrast to the prevailing strategies, we estimate the trend and rate of change of BMI values by birth cohorts stratified by gender and ethnicity born 1882-1986. We use loess additive regression models to estimate age and trend effects of BMI values of US-born black and white adults measured between 1959 and 2006. We use all the NHES and NHANES survey data and find that the increase in BMI was already underway among the birth cohorts of the early 20th century. The rate of increase was fastest among black females; for the three other groups under consideration, the rates of increase were similar. The generally persistent upward trend was punctuated by upsurges, particularly after each of the two World Wars. That the estimated rate of change of BMI values increased by 71% among black females between the birth cohorts 1955 and those of 1965 is indicative of the rapid increases in their weight. We infer that transition to post-industrial weights was a gradual process and began considerably earlier than hitherto supposed.