The number of children who are overweight or obese has increased threefold in the past few decades, and today it is estimated that 35 to 40 percent of children and adolescents are overweight, health experts said.

A person is considered overweight if his or her body mass index is greater than the 85th percentile for his or her age and sex.

A person is considered obese if the index is more than the 95th percentile, said Joe Eisenmann, assistant professor of health and human performance.

Jill Weber, nutrition and health field specialist for ISU Extension, said along with being physically unhealthy, children who are overweight or obese usually have lower self-esteem.

Some of Eisenmann’s most recent research looks at stress in children and adolescents and how it correlates with an individual’s body weight.

He said lack of sleep is one stress that relates to body weight. Children who sleep an average of eight or fewer hours a night are two and a half times more likely to be overweight or obese than children who sleep an average of 10 hours a night.

Another study Eisenmann did found women who gained more weight during pregnancy produced babies with higher birth weights, and these babies had a tendency to have problems with weight throughout their life.

Robin Hamre, obesity prevention program team leader for the Centers for Disease Control and Prevention, said the social culture of the United States prevents people from eating a healthy diet.

She said because Americans live a hectic lifestyle many people eat a lot of fast food.

Janeann Stout, associate dean of the College of Family and Consumer Sciences, said Iowa has the highest percentage of households in which both parents are employed, which makes unhealthy eating a more prevalent problem for Iowa.

Hamre said people would benefit from taking the time to cook at home. Hamre also said children are not as active as they should be.

She said parents should turn off television sets and prompt their children to get outside and play.

Television not only makes children inactive, it also sends messages to eat more food, she said.

Stout said the way people define their community can also contribute to childhood obesity.

She said some communities may be more accustomed to walking rather than driving. People who do not feel safe in the places they live, however, would walk less, if at all.

Helping children have a supportive environment is important, and working with schools can decrease the number of overweight and obese children, Weber said.

“We need to look further than the simple solution of activity and diet to prevent and treat childhood obesity given how complicated and multifactorial of a disease obesity is,” Eisenmann said.

Weber and Hamre joined 28 other professionals to speak about childhood overweight and obesity prevention at a two-day conference Monday and Tuesday at the Gateway Center Hotel.

Two hundred and thirty people attended the conference, which was geared toward school personnel, public health partners, dietitians and community planners.