Tracking of Obesity in Childhood into Adulthood: Effects on Body Mass Index and Fat Mass Index at Age 50

<b><i>Background:</i></b> Obesity is present in 17% of US youth, age 2-19 years, but the extent to which obesity in childhood is associated with higher BMI and fat mass in middle age is unclear. In this study, links between childhood body size and BMI and body composition at age ∼50 were assessed. <b><i>Methods:</i></b> Child Health and Development Studies participants, born between 1960 and 1963 in Alameda County, and still living in California, from whom anthropometric data were collected at age 5, 9-11, and/or 15-17 years were followed-up at age ∼50 for anthropometric outcomes (251 women; 249 men). Linear regression analyses assessed whether overweight (85th to <95th BMI percentile) or obesity (≥95th BMI percentile) at age 5 were associated with BMI, fat mass index (FMI), and lean mass index (LMI) at age ∼50. <b><i>Results:</i></b> At age 50, participants with obesity at age 5 had BMI scores that were 6.51 units higher [95% confidence interval (CI) = 3.67-9.35] than participants who were normal weight at age 5; FMI and LMI scores were 4.15 (95% CI = 1.98-6.32) and 2.36 (95% CI = 1.45-3.26) units higher, respectively. However, obesity experienced at age 5 had only a modest positive predictive value for predicting the presence of obesity at age 50 (67%), whereas obesity present at age 15-17 had a higher positive predictive value (86%). <b><i>Conclusions:</i></b> The experience of obesity at age 5 for members of this birth cohort was associated with significantly higher BMI, FMI, and LMI at age ∼50.