A new report that studied kids throughout childhood found that those who are obese at five years old are more likely to be heavy later in life.
While other studies have hinted at that trend, those have generally involved what’s known as prevalence of the condition — or the proportion of a population, at a given time, that is considered obese. Such information doesn’t suggest the risk of developing obesity, which is revealed by studying a population over specific periods of time. So in the latest study, published in the New England Journal of Medicine, scientists tracked a group of 7738 children, some of whom were overweight or obese, and some who were normal weight, from 1998 (when they were in kindergarten) to 2007 (when they were in ninth grade). They found that the 14.9% of five-year-olds who were overweight at kindergarten were four times more likely to become obese nearly a decade later than five-year-olds of a healthy weight.
During the study, the researchers measured the children’s height and weight seven times, which allowed them to record the incidence of obesity almost yearly. Overall, since most of the children (6807) were normal weight at the start of the study, the children’s risk of becoming obese decreased by 5.4% during the kindergarten year and by 1.7% between the fifth and eighth grades. But the five-year-olds who were overweight, defined as having a body mass index (BMI) within the 85th percentile for their age group were significantly more likely to become obese, which the scientists defined as a BMI within the 95th percentile of their age group as time went on. Among kids who became obese between the ages of five and 14, about half had been overweight in the past and 75% were in a high BMI percentile at the start of the study.
Obesity is connected to a high risk of chronic conditions such as diabetes, heart disease, and stroke among adults, and young children who spend more years overweight or obese may be putting themselves at even higher risk of these diseases, the scientists say.
The study highlights the dynamic between early weight gain and obesity, and the researchers say future work should focus on understanding what contributes to a child becoming overweight so early in life. The results suggest that education about weight gain and obesity prevention efforts may need to start earlier with families of young children, before youngsters become locked in a condition that’s difficult to change.