Heavy Reading for Weight Watchers
Two recent articles, one in the New England Journal of Medicine and the other in Pediatrics, make for some interesting reading on the topic of childhood obesity.
The NEJM article[6] begins with a straightforward and (sadly) intuitive statement: There is an increase in the prevalence of childhood obesity in the United States. What is poorly understood is the incidence and timing. When do children become overweight and obese? According to the study, if we know when children are more likely to put on unhealthy weight, we will be able to identify vulnerable ages and target certain groups, in a wiser and hopefully more effective use of resources.
The main findings of the study are:
1. Among a representative cohort of 7738 kindergarteners (in 1998 and followed into eighth grade in 2007), overweight children (mean age, 5.6 years) were four times as likely as normal-weight children to become clinically obese.
2. Yet the annual incidence of obesity—the number of children who tipped into the obesity category—actually decreased over this period, from 5.4% during kindergarten to 1.7% between fifth and eighth grade.
3. By the time a child enters kindergarten, when 12.4% are obese and an additional 14.9% are overweight, a significant period in which to intervene and hopefully prevent childhood obesity has already been missed.
Questions remain to be answered about how early the obesity trajectory begins and the role of maternal, home life, and preschool environments. In a nutshell, we need to look at the crucial early childhood period, before the age of 5 years.
Across the Atlantic Ocean, the authors of the Pediatrics article did just that.[7] Beginning at birth, the researchers sampled 546 children who were part of a larger cohort followed from birth with body mass index (BMI) measurements. On the basis of the measurements, three periods of timing for adiposity rebound (AR), the period in childhood when BMI begins to increase from its nadir, were determined. Very early AR occurs before 43 months of age; early AR is seen between 43 and 61 months; and later AR is characterized by its appearance in children older than 61 months.
When these children were followed to the age of 15 years, the conclusion was obvious: The earlier a child's BMI started to increase, especially if AR occurred before 43 months of age, the more likely that their BMI would be higher at 15 years. Incidentally, children of obese parents were found to be at the greatest risk for early AR.
In the lay media and in regular conversations, obesity is often discussed in conjunction with poor dietary choices, marketing forces, lack of exercise, and other factors. All are true but may, according to these studies, be the equivalent of too little, too late. The focus of both clinicians and policy-makers probably needs to be on public health interventions in early childhood, more attention to weight trends of babies and toddlers, and better intervention approaches for children of obese parents.
Medscape Pediatrics © 2014 WebMD, LLC
Cite this: L. Gregory Lawton. 2014's Pediatric 'Great Eight': The News You Need to Know - Medscape - Dec 19, 2014.
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