Intelligence test score and educational level in relation to BMI changes and obesity

Objective: To investigate whether intelligence and education are related to subsequent BMI changes and development and persistence of obesity in men from young adulthood through middle-age. Research Methods and Procedures: Subjects were selected among men (median age, 19 years; examined between 1956 and 1977) appearing at Danish draft boards: a group with juvenile-onset obesity, including all men with a BMI of greater than or equal to 31.0 kg/m(2); and a nonobese group randomly selected as a 1% sample of the study population. The obese group and 50% of the nonobese group were invited to participate in follow-up studies between 1982 and 1984 and between 1992 and 1994. Among 907 men with juvenile-onset obesity and 883 nonobese men, age, examination region, intelligence test score, education, and BMI from baseline to first follow-up were analyzed by multiple linear and logistic regressions analyses. Results: Education and intelligence, analyzed separately, were inversely related to BMI changes in both groups and to the development of obesity in the nonobese group. When adjusted for education, the association between intelligence score and BMI changes and development of obesity vanished, whereas the inverse relationship for education persisted only for BMI changes. Intelligence score was not associated with the persistence of obesity in the obese group, whereas inverse relationships were found for education. Discussion: Intelligence test score was inversely related to risk of BMI changes and the risk of development of obesity, perhaps with education acting as a mediator or indicator of cognitive ability. Education, but not intelligence, was inversely associated with risk of remaining obese.