November 24, 2013
John DiTraglia MD
Everybody knows we have gotten fatter. But when did we start getting fatter? Studies show that the rate of overweight and obesity among children has stopped going up in the last 10 years. The rate hasn’t gone down, but it’s not going up anymore. A report in October’s Pediatrics shows that adolescents are exercising more and eating less sugar over the last 10 years. (1) Epidemiological studies that try to figure out why things happen to free range humans are notoriously wrong. If kids are exercising more and eating less sugar at an ever increasing rate over those ten years why has the rate of obesity plateaued instead of gone down? Still it is interesting to look at even longer trends.
In 1929, Arthur Morgan, then president of Antioch College in Yellow Springs, Ohio, posed the question, “What makes people different?”. He approached Samuel Fels, a Philadelphia businessman and philanthropist, with an idea for a longitudinal study from birth to adulthood. Mr. Fels gave Morgan the backing needed to begin the study, and Lester W. Sontag M.D., Antioch College?s physician, was appointed the first director of the Fels Longitudinal Study (FLS) in 1929. Since then this study has recruited children primarily from three counties in the Dayton, Ohio area.
In this month’s journal Obesity (2) is a report on 1,116 boys and girls from the FLS study who have been weighed and measured since 1930, much longer than the National Health and Nutrition Examination Survey (NHANES) data that started in the early 1960’s. It would appear that their obesity epidemic started after birth year 1970 for boys and 1980 for girls. Before that kids were obese at a steady low rate. For “overweight” as opposed to “obesity” the trend seems to have been more gradual for girls. But boys were not getting overweight at an increasing rate until 1970 when their obesity epidemic started.
So what does this mean? There was the Depression and World War II. Rates of heart attacks and arteriosclerosis were going up fast. There was an epidemic of smoking. Epidemiology is so confusing.
1. Iannotti RJ, Wang J. Trends in physical activity, sedentary behavior, diet and BMI among US adolescents 2001-2009. Pediatrics 2013; 132:606-14.
2. Hippel PT, Nahhas RW. Extending the history of child obesity in the US: The Fels Longitudinal Study, birth years 1930-1993. Obesity 2013; 21:2153-6.