(CBS) Childhood obesity affects about 17 percent of U.S. kids and teens, three times the amount seen nearly three decades ago. Now, the American Heart Association (AHA) is now reporting a troubling, growing increase in the most severe forms of childhood obesity.
"Severe obesity in young people has grave health consequences," warned study author Dr. Aaron Kelly, a researcher at the University of Minnesota Medical School in Minneapolis. "It's a much more serious childhood disease than obesity," he said in an AHA statement.
Researchers reviewed data on U.S. children, and determined 5 percent had severe obesity. They published a "scientific statement" in the AHA's journal Circulation, which is a policy statement that defines severe childhood obesity for other doctors.
Childhood obesity is diagnosed the same way as it is for adults, through taking body mass index (BMI) measurements, which are ratios of height in inches over weight in pounds. While adults have set numerical ranges that can determine a diagnose -- for example, those with a BMI of 25 to 29.9 are overweight, while 30 and above are considered obese -- children are often assessed based on how their body mass compares to that of their age group.
Kids and teens are considered overweight if their BMI falls into the 85th to less than 95th percentile of others of their age and gender, while obesity is diagnosed if a child has a BMI equal or greater to 95 percent of their peers. Overall, one-third of U.S. children are considered obese or overweight.
The AHA's scientific statement reveals a new definition for those who are severely obese: Having a BMI at least 20 percent higher than the 95th percentile for their age and gender, or a BMI of 35 or higher.
That means a 7-year-old girl of average height that weighs 75 pounds or a 13-year-old boy who weighs 160 points would be considered severely obese.
The statement calls for "innovative approaches" to fill the gap between early interventions lifestyle changes and medication, and the final intervention -- weight loss surgery. Weight loss, or bariatric, surgery isn't always appropriate for severely obese kids, said Kelly.
Severely obese children are often difficult to treat, pointed out cardiologist Dr. Valentin Fuster, director of Mount Sinai Heart at The Mount Sinai Medical Center in New York City. He told CBSNews.com from his experience, weight management is difficult for these children because they tend to want to eat more -- a process driven by hormones -- while some have such low self-esteem from their lifelong struggles with weight, they simply give up trying.
"Somehow you think you've got it, but they come back," said Fuster of managing weight in severely obese kids. "We are dealing with a problem."
He added, "This is why it's so important to know the reasons for why you're obese."
Fuster, who previously was president of the AHA, said it's too simple to say kids are eating too much. He said early interventions should target anxiety, family or genetic-related issues that may be contributing to obesity at such a young age. He is currently conducting studies in Colombia and Spain that track children from a very young age, and educate them on healthy eating and how weight is gained. The results so far suggest such attempts are helpful, he said.
Specific suggestions from the statement's authors include conducting new studies on the effectiveness or lifestyle modifications like diets and physical activity plans and finding out how well kids will stick to them. They also advocated for more drug and device research, as well as looking into weight loss surgery's safety for children.
Not putting a child towards a path of a healthy weight could contribute to health risks later in childhood or come adulthood. Childhood obesity can increase risk for Type 2 diabetes, stroke, cancer, joint pains from osteoarthritis and cardiovascular problems like high blood pressure, high cholesterol and early signs of atherosclerosis, which can clog the arteries and lead to heart attacks and strokes.
Childhood obesity has also been linked to mental health risks from bullying or eating disorders.
Nationwide, overall childhood obesity rates seem to be leveling, or even falling slightly. In August, researchers from the Centers for Disease Control and Prevention (CDC) reported drops in obesity rates among preschoolers living in 18 states and the U.S. Virgin Islands.
Last December, a CDC study in JAMA showed declines in childhood obesity prevalence from 15.2 percent of kids in 2003 to 14.94 percent in 2010 for the latest report.
But, Kelly noted that while the national problem may be leveling, severe obesity rates among children are on the rise.
Fuster warned those rising rates are contributing to a nationwide health crisis.
"All society should be aware that this is a huge problem, leading to an epidemic of cardiovascular diseases," he said.
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