The Spread of Obesity in a Social Network

Abstract

In the report on the spread of obesity in a social network, by Christakis and Fowler, and the accompanying editorial by Barabási (July 26 issue),^1,2 variables of social and economic status (SES) are not mentioned. Social networks conceal a high degree of social homogeneity — that is, people are more likely to network with people at similar income and educational levels — and we suspect that they may operate differently in different contexts. For example, the way a social network affects the incidence of obesity in a community where most people have a low educational level and cannot afford a healthy diet is likely to differ from the way it affects an affluent and well-informed community. In 2000, obesity in the United States was reported to be highest among black women and people who had not completed high school,³ and among black women, a low socioeconomic position predicts an early onset of obesity.⁴ SES variables should be included in any interpretive model, and public health policies for the prevention of obesity should take into account the SES characteristics of the communities they are supposed to benefit.⁵