Darius Lakdawalla on the Economics of Obesity

Episode Summary

Executive Summary: Russ Roberts and economist Darius Lactawala examine the long-run rise in obesity, arguing it is driven less by a single culprit like fast food and more by cheaper calories, technological change, and increasingly sedentary lifestyles. They also explore the role of genetics, health insurance, norms, and the unresolved policy question of how much society should insure or penalize weight-related behavior.

Main Topics: The scale and measurement of obesity (Priority: 5/5): Lactawala explains how obesity is measured with BMI and notes that U.S. obesity rates have risen dramatically in recent decades, with serious health implications especially for younger people and children. Historical rise in body weight (Priority: 5/5): The conversation places modern obesity in a centuries-long trend of rising weight, using historical data from Union Army veterans to show Americans were already becoming heavier long before McDonald's and modern fast food. Cheaper food and caloric abundance (Priority: 5/5): A major explanation for rising weight is the secular decline in food prices, especially calorie-dense processed foods, which makes overeating cheaper and more attractive. Sedentary work and lifestyle change (Priority: 4/5): Roberts and Lactawala discuss how industrial and technological change reduced physically demanding labor and housework, while leisure became more sedentary, lowering daily calorie expenditure. Income, education, and health gradients (Priority: 4/5): The interview explores why richer and more educated people tend to be healthier and often thinner, emphasizing lifetime income, health preferences, and the difficulty of separating income effects from knowledge effects. Policy, insurance, and personal responsibility (Priority: 5/5): They debate whether obesity should be treated like an involuntary medical risk or partly as a consequence of personal choice, especially in the context of employer health insurance and possible premium discrimination. Future trends, norms, and innovation (Priority: 3/5): The discussion ends with speculation that future technology and rising wealth could eventually slow obesity by making health-oriented choices easier, while social norms and medical innovation may also reshape outcomes.

Key Arguments: Obesity has tripled in roughly 25-30 years in the U.S., rising from about 7-8% to about 20-25%, making it a major public health issue. The obesity trend is not new; body weight has been rising for centuries, so modern fast-food companies are not the sole cause. BMI is used because it correlates with mortality: very low and very high values are associated with worse survival outcomes. Food has become cheaper over time, and calorie-dense foods have become especially cheap due to technological improvements in processing and preservation. The main driver of recent obesity is not a change in diet composition alone, but a rise in total calorie intake made easier by cheap calories. Earlier in the 20th century, rising obesity also reflected reduced physical labor at work and at home, plus more sedentary leisure. Richer people tend to be healthier and thinner because health is a normal good: as income rises, people can afford more health-preserving behavior and services. Obesity should not be viewed purely as an 'epidemic' imposed by outside forces; personal choice and incentives matter significantly. There is still uncertainty about the roles of genetics versus behavior, especially in designing insurance and public policy. Future medical and technological innovation could reduce the health costs of obesity, while greater wealth may eventually increase demand for healthier body weights.

Data Points: U.S. obesity rate increase: Tripled over the last 25-30 years - Lactawala describes the modern rise in obesity among Americans. Obesity prevalence in the U.S.: Approximately 7-8% to 20-25% - He gives the rough historical increase in adult obesity rates. Historical weight gain: 10-15% increase; some ages up to 20% - Comparison of Union Army veterans' weights with later Americans. Average male weight example: About 170 lbs today vs. about 140s-150 lbs a century ago - Illustrative comparison for a man of roughly similar height. Age group health caution: Strongest concern for ages 27, 30, 40, and children - He notes obesity is especially harmful earlier in life. Countries with biggest changes: Britain, Australia, United States, Canada - English-speaking countries experienced the largest weight gains. BMI formula: Weight in kilograms divided by height in meters squared - Definition of the body mass index used to assess obesity.

Pivotal Quotes: "It's definitely true that Americans are getting fatter." — Darius Lactawala: Opening summary of the central empirical claim about obesity trends. "We actually seen food prices falling and falling, not just over the past 30 years, but over the past 100, 120 years, we've seen food getting cheaper and cheaper." — Darius Lactawala: Explaining why fast-food advertising is not the main explanation for rising obesity. "People are paid to sit at their desks and not exercise." — Darius Lactawala: Describing the modern shift from physically demanding labor to sedentary work.

Implications: Listeners should see obesity as a complex outcome of incentives, technology, and lifestyle—not just willpower or advertising. For policy, the big open question is whether insurance should subsidize weight-related risks or more directly reward healthier behavior.