According to a new study in Economic Inquiry, an individual's body weight depends not just on physiology and economic circumstances, but also on average body weight of the population at large.
The study is the first to quantitatively model body weight distribution based on the combined outcome of economic, biological and social influences.
The findings complement those of a recent, high profile study that found direct evidence of social contagion of obesity within social networks. Although Burke and Heiland studied trends in the aggregate weight distribution, rather than following specific individuals over time, the evidence of person-to-person contagion provides strong support for their modeling approach.
"Behavior governing weight depends not just on health considerations but also on the desire to appear normal and attractive," say authors Mary Burke and Frank Heiland. As a result, any change that causes average weight to increase, such as a decline in food prices, will lead to additional weight increases because the weight level considered , normal, will rise. This is an example of a social multiplier effect. The authors find that their integrated model, describing the effects of economic and social change on a physiologically heterogeneous population, does a better job of explaining changes in the weight distribution over the past thirty years than do models based on economic change alone.