CHICAGO -- More than a third of disadvantaged 3-year-olds in Baltimore and other major U.S. cities are overweight or obese, according to a new study that supports the notion that the struggle with obesity often begins in early childhood.
Hispanic children were most at risk, with 45 percent either overweight or obese.
The study's authors at the University of Wisconsin in Madison also identified several practices that may protect kids from excessive weight gain, including breast-feeding for at least six months and not allowing children to take a bottle to bed.
"What we know really tells us that this age is a critical period," said Dr. Jonathan Necheles, a pediatrician with the obesity prevention program at Children's Memorial Hospital in Chicago who was involved with the study.
"The older these kids get, the harder it gets" to change their eating habits, he said.
Although some nutrition experts hailed the results as a call to action, using the terminology of obesity to describe very young children remains a contentious issue.
The federal Centers for Disease Control and Prevention does not refer to anyone younger than 20 as obese, since rapid growth early in life makes it difficult to compare desirable weights for children and adults. Instead, the CDC uses the terms "overweight" or "at risk of overweight" to classify children at the upper end of their peer group's body-mass index, or BMI, a number used to gauge the relationship of weight to height.
In contrast, the American Obesity Association holds that the same language of obesity should be used for children and adults, in part because heavy children are more likely to become obese adults and face a range of health problems such as diabetes and high blood pressure.
Despite such differences, both organizations agree that more children are becoming overweight, creating a looming national health threat. Nationwide, the number of children who fall in the 95th percentile of BMI - the definition of obese - has more than doubled over the past two decades, to nearly 19 percent in 2004.
The new study, published online yesterday in the American Journal of Public Health, came up with even higher numbers for its target group of low-income children randomly selected from 20 major cities, including Baltimore. In all, 35 percent of the 3-year-olds were either overweight or obese - a striking figure, several experts said.
"These numbers are more dramatic than people might have expected," said Dr. Dennis Bier, director of the U.S. Department of Agriculture's Children's Nutrition Research Center at Baylor College of Medicine. "It quantifies what general belief and other data have suggested - that obesity starts very early in life."
Many studies have shown that Latinos are at severe risk for obesity, but the new report suggests Latino children may face unique challenges. The researchers could not fully explain the higher obesity rate among Latinos, but they noted that previous studies have shown Latina mothers are more likely than white or black mothers to worry when their children say they are no longer hungry.
In addition, some research has shown that mothers who are Hispanic or African-American may tend to consider chubbiness a sign of a healthy baby.
"Cultural perceptions like that can be very powerful and difficult to change," said study leader Rachel Kimbro, a medical sociologist at the University of Wisconsin.
Having an obese mother put children at risk for obesity, but when those children were breast-fed their chances of being obese went down significantly. The authors said that suggests doctors may want to give obese mothers extra encouragement to breast-feed their infants.
The study also found that 14 percent of 3-year-olds in Hispanic households took a bottle to bed - more than twice the rate of white or black children. Pediatricians say parents should never send children to bed with a bottle because it can contribute to tooth decay as well as weight problems.
About three-fourths of children in the study came from families that received federal food assistance. That's consistent with other research showing an increased risk of obesity among low-income families, especially those who live in "food deserts" where grocery stores are scarce.
"Good quality, fresh food is not available in a lot of these neighborhoods," Kimbro said. "Many mothers in our sample had to walk or take the bus or a taxi to the grocery store. They're going to choose food that's going to last, and that's not going to be fresh food. It's going to be food that's high in calories."
No one has completely solved the puzzle of how to prevent obesity among children. Indeed, many studies have shown that efforts to attack the problem aggressively - for example, by banning all fattening foods from a child's diet - can backfire and lead to greater interest in such foods.
But experts said the new study underscores the importance of monitoring troubling trends in a child's BMI measurements. A little chubbiness might not be a problem, but, in general, a child's growth in height should match his or her weight gain over time.
"I don't think the message is to put your 3-year-old on a diet," Kimbro said. "But when you increase their access to fruits and vegetables, and decrease things like soda, that's helpful. Parents need to make sure they have healthy foods available and that they model healthy eating behavior."
Jeremy Manier writes for the Chicago Tribune.