Effects of Lay Theories of Obesity on Body Mass: Theory, Evidence, and the Role of Marketing

Abstract:

Obesity is a growing problem worldwide, but despite much research into its causes, scientists have largely neglected to investigate laypeople’s personal beliefs. In a series of studies across five countries on three continents, we find that (1) people mainly believe either that obesity is caused by a lack of exercise or by a poor diet, and (2) laypeople who implicate a lack of exercise are more likely to actually be overweight than those who indict poor diet. This effect holds even after controlling for several known correlates of BMI, and occurs because people who implicate insufficient exercise tend to eat more than those who indict poor diet. An analysis of the antecedents of these lay beliefs indicates a dual role played by food marketers in the rise of obesity