Effects of Obesity in United States

Effects of Obesity in United States

Introduction

Obesity has long been a problem in North America, especially in the United States. In 2007, the United States had one of the highest rates of obesity in the world, with its occurrence in the adult population doubling between 1980 and 2002, and tripling in children during the same period. In 2003-04, children (aged 2-19) had very high levels of obesity, with 17.1 percent of them found to be overweight, and for adults (aged 20 and over), 32.3 percent were also found to have been overweight.

Driving Factors

While popular media might place blame on a multitude of factors such as the fast-food industry, economists have attempted to build basic models to understand the weight trends. In simple terms, weight gain is the result of an increase in calories ingested over calories expended. An increase in calories can result from greater food intake at each meal, more meals of equal caloric intake, or changes in food preparation to include more calories.

However, a decrease in calorie expenditure can be the product of a more sedentary lifestyle through a decrease in energy expenditure at work or even in leisure activities. The challenge lies not in just documenting the changes in the above in relation to the changes in weight, but to pin down the causal link between these myriad factors in the observed trend in increased obesity. Despite the paucity of necessary data tracking the daily caloric intake and expenditure values for large groups of individuals over long periods of time, economists have used clever models with limited data to uncover some of these underlying relationships.

Role of Technology

Technological change has impacted both the supply and demand for obesity. On the supply side, technology has made the agricultural production process more efficient, such that the price per calorie has become much cheaper, increasing the demand for calories. On the demand side, technology has made the time spent at work more sedentary. For example, because work was more strenuous in more agrarian and early industrial societies, laborers were essentially paid to exercise. However, post-Industrial Revolution, the nature of work itself has changed; individuals are essentially paid in terms of foregone leisure. In essence, individuals are paid to substitute out-of-work leisure exercise for exercise typically undertaken at work. Empirical estimates by RAND economist Darius Lakdawalla and University of Chicago economist Tomas Philipson show that 40 percent of the recent increase in weight is due to the lower food prices from agricultural innovation, while 60 percent is a product of declining physical activity due to technological improvements in home and market production.

While this model does explain the long-run changes in obesity trends, it falls short of explaining the large increase in obesity in the United States starting in the 1980s, a time during which commensurate changes in technology do not exist. Therefore, Harvard economists David Cutler, Edward Glaeser, and Jesse Shapiro study the role of technology in increasing caloric intake, as it has decreased the ...