Omitting the Obvious: Cohort Effects in 19th and 20th Century BMI Variation

Peer and cohort effects are important in health economics, and obesity may be related to social relationships, where obese individuals interact with other obese individuals. There were significant 19th century cohort effects, where BMIs were related to the cohort that an individual belonged. After accounting for individual relationships between BMI, demographic, socioeconomic, and residential characteristics, there were significant cohort effects associated with race, residence, and age. Moreover, cohort effects reduce the size of the individual relationships between BMI, race, and age, but results are mixed for BMI and residence. This indicates that historical cohort effects are important in BMI and obesity studies.