The researchers looked at data from more than 26,000 children age 2 to 19 in the United States who participated in the National Health and Nutrition Examination Survey. They found that rates of overweight and obese children have been trending upward since 1999, with significant increases seen recently in the number of severely obese children.
Severe childhood obesity rates have more than doubled since 1999, according to the study. In 1999-2000, less than 1% of children fell into the Class 3 obesity category - meaning they had a body mass index 140% higher than their peers. In 2011-2012, 2.1% of children were in the same category. An additional 5.9% met the criteria for Class 2 obesity.
"I think there's certain kids who are at greatest risk for obesity," said lead study author Asheley Skinner, an associate professor of pediatrics at the University of North Carolina School of Medicine. "When you put them in an environment like this one... they're more likely to gain a whole lot of weight. That's part of what's going on."
The risks associated with that extra weight are scary.
Obese children are more likely to have high cholesterol, high blood pressure and type 2 diabetes later in life, according to the Centers for Disease Control and Prevention. They're also at risk for bone and joint problems, sleep apnea and psychological problems due to poor self-esteem. Studies show that obese children and adolescents are likely to remain obese as adults.
A separate study published in the journal Pediatrics this week estimates an obese child will incur anywhere from $12,000 to $19,000 in additional medical costs throughout his or her lifetime compared to a normal weight child.
Image: Blocks spelling "Obese," via Shutterstock