UTSW study identifies risk factors for severe obesity in kindergartners

By Jan Jarvis

By the time they start kindergarten, 6 percent of children in the United States are already severely obese.

Dr. Glenn Flores, Professor of Pediatrics and Clinical Sciences at UT Southwestern Medical Center, reported in a recent study that the reasons for this unsettling statistic range from children drinking sugary drinks to poor bedtime habits. Exceeding the 85th percentile for Body Mass Index, or BMI, at an early age is one of the most powerful predictors of severe obesity, Dr. Flores said.

Factors Associated with Severe Obesity graphic

“There are multiple risk factors associated with severe obesity,” said Dr. Flores, also head of general pediatrics. “That’s why it is really important to prevent this as soon as possible.” 

Severe obesity is defined as exceeding the 99th percentile of BMI. The number of children meeting this criterion has increased by 300 percent since 1980, when 1 percent of youngsters were severely obese, said Dr. Flores, whose study on obesity in kindergartners was published in November in the online edition of the International Journal of Obesity.

Severe childhood obesity is associated with multiple cardiovascular risk factors, including elevated levels of cholesterol, triglycerides, blood sugar, and blood pressure. Research also documents that severely obese children have school absenteeism rates 11 percent greater than those of healthy-weight youngsters.

Prior to this study, little was known about the predictors of severe obesity, and no studies had examined risk and protective factors for this age group. Dr. Flores analyzed a nationally representative longitudinal population of 14,000 U.S. children followed from birth through kindergarten age.   

This study found that even before the child is born, factors such as severe maternal obesity and gestational diabetes were associated with three times the likelihood of severe obesity in kindergartners. Latino or multiracial ethnicity and five or more adults in the household also were associated with severe obesity.

Older maternal age at the time of the first child’s birth was associated with reduced odds of severe obesity. 

To prevent severe obesity, parents should work with their health care providers to identify children at high risk, Dr. Flores said. Starting at 9 months of age, a child’s BMI and growth curve should be monitored.

Parents also can reduce obesity risks by taking their child outside to walk or play a few times a week, starting at 9 months of age. Maintaining strict bedtime rules for preschoolers and making sure children eat fruit at least weekly also may prevent obesity.


Dr. Flores holds the Judith and Charles Ginsburg Chair in Pediatrics.