Abdominal obesity increased more than 65 percent among boys and almost 70 percent among girls between 1988 and 2004. The finding of growing girth is significant because abdominal obesity has emerged as a better predictor of cardiovascular disease and type 2 diabetes risk than the more commonly used Body Mass Index, a weight to height ratio that can sometimes be misleading.
As the first nationally representative study to document the increase in children's belly fat, the study in today's Pediatrics paints a bleak picture for these children who have a higher risk of heart disease, adult-onset diabetes and metabolic syndrome. The good news is that, for children and adolescents, the health effects are often reversible through improved lifestyle for weight loss.
"Kids, teens and adults who have early stages of atherosclerosis in their arteries can have a healthy cardiovascular system again," said Stephen Cook, M.D., an assistant professor of Pediatrics at the University of Rochester Medical Center's Golisano Children's Hospital at Strong and an author of the study about childhood abdominal obesity. "Older adults who have plaque build up have a much harder battle, especially if the plaque has calcified."
Measuring waist circumference is not a "vital sign" normally taken in a visit to the doctor. A BMI is commonly calculated at a well visit, but there are limitations to those measurements. A very muscular person may register a high BMI score, even if he is very healthy and has an average waist circumference. On the flip side, a sedentary child may not register a very high BMI score, but if he carries a lot of fat around his middle, he may be at a higher risk for health problems than other children with the same BMI score.
Cook said there is no gold standard yet for how waist circumference should be measured and no consensus yet on the cut-off point for abdominal obesity. However, he added, the study should be a warning for physicians and parents to limit sedentary activities, such as TV and computer time, and to teach and model healthy eating and exercise behaviors; childhood obesity is a serious and growing problem - perhaps even more than people already believe.
Although increases in Body Mass Index scores have raised concerns about U.S. children's short- and long-term health, the increase in the percentage of abdominally obese in children appears to have increased even faster than overweight measured by BMI scores. According to data from the National Health and Nutrition Examination Survey (NHANES) between 1999 and 2004, the percentage of 6- to 11 year-old children with high BMI scores rose about 25 percent (15.1 percent in 1999-2000 to 18.8 percent in 2003-04). But the increase in abdominal obesity of the same group over the same period was even more dramatic, more than 35 percent (14.2 percent in 1999-2000 to 19.2 percent in 2003-04).
"Those increases only grow more alarming as you tease out specific age groups over longer periods of time," Cook said. "For example, between the 1988-1994 data and the 1999-2004 data, the largest relative increase in the prevalence of abdominal obesity occurred among 2- to 5-year old boys - 84 percent - and 18- to 19-year-old girls - 126 percent."