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Overweight or underweight children who are seen in the emergency department are more likely to be admitted to the hospital, and to stay longer, than normal-weight youngsters, according to a study reported Monday at the American College of Emergency Physicians' annual meeting in Boston.

The bottom line is, like anything else, being in the middle (weight) range is best, Dr. Adam Singer from the State University of New York at Stony Brook told Reuters Health.

Singer and colleagues took a look back at 6,304 children who were seen in the emergency department in 2007.

Of the 12 percent of children who were admitted, 6.9 percent were underweight, 16.8 percent were at risk of being overweight, and 18.4 percent were overweight.

A deeper look at the data revealed that children outside of the healthy weight range (both under and over) were more likely to be admitted to the hospital (47 percent versus 41 percent).

Fewer boys were at a healthy weight than girls (54 percent versus 63 percent) and underweight patients were younger than patients in the other weight categories.

Gender, age and obesity class were all associated with hospital admission: Boys were more likely to be admitted than girls, younger children more likely than older, and healthy-weight children less likely than overweight.

We can speculate that obese children may be more likely to get sick, and when they get sick, they may be more likely to have severe illness -- regardless of whether or not the illness is specifically related to obesity, such as diabetes -- compared to normal-weight children, Singer said.

This study gives us yet another reason to emphasize the importance of optimizing weight and preventing obesity in children. It's one more piece of evidence that obesity in children impairs health, he stressed.

We've spent years focusing on obesity in adults and the association with heart disease, liver disease, (high blood pressure), diabetes, and so forth, but only recently have we focused on children, Singer said. Obesity is a heavy cost to children, to society, and to the economy, since each additional admission and day spent in the hospital is costly.