Little is known about the prevalence of child obesity in the US before the first national survey in 1963. There is disagreement about whether the obesity epidemic is entirely a recent phenomenon or a continuation of longstanding trends.

Design and Methods

The BMIs of 1,116 children who participated in the Fels Longitudinal Study near Dayton, Ohio were analyzed. Children were born between 1930 and 1993 and measured between 3 and 18 years of age.


Between the birth cohorts of 1930 and 1993, the prevalence of obesity rose from 0 to 14% among boys and from 2 to 12% among girls. The prevalence of overweight rose from 10 to 28% among boys and from 9 to 21% among girls. The mean BMI Z score rose from +0.25 to +0.72 among boys and from −0.11 to +0.26 among girls. Among boys, all these increases began after birth year 1970. Among girls, obesity began to rise after birth year 1980, but overweight and BMI Z-scores were already rising as early as the 1930s and 1940s.


Most of the results suggest that the child obesity epidemic was recent and sudden. The recency of the epidemic offers some hope that it may be reversed.