Obesity Rate for Low Income Children Not Higher

Results a Surprise, Different from Adult Findings

While America's lowest income adults have a higher incidence of obesity than higher income adults, surprisingly the same isn't true for low income children, according to a new University of Maryland study. The lowest income children do not have a higher rate of obesity.

The study also found that federal food programs, including the Food Stamp and National School Lunch and Breakfast Programs, do not affect the incidence of obesity in the poorest children. The study appears in the September issue of the Journal of Policy Analysis and Management.

"These findings were counter to our hypotheses," says Sandra L. Hofferth, professor of family studies at Maryland, who, with Maryland research assistant Sally Curtin, co-authored the study.

"Based on earlier research that shows that low-income adults have high obesity rates, we hypothesized that children from the lowest-income families would be more likely to be overweight. We also thought that the more money a family receives in Food Stamp Program benefits, the more likely the children would be overweight.

"Our results proved otherwise," Hofferth says. "But we can't use these findings as an excuse to ignore the nutritional content of school food programs. Children in families just above the poverty line are at risk of overweight, and meals too high in fat and cholesterol could reinforce that tendency."

Children's Obesity Quadruples

Hofferth and Curtin's study was spurred by the skyrocketing rate of obesity in children. The percentage of overweight children ages 6-11 years quadrupled between 1965 and 2002, going from four to 16 percent.

"And because low income families would have less money to spend on food were it not for food programs, food programs for low-income families are blamed," Hofferth says. "We wanted to find out whether there is a relationship between family income and a child's being overweight and whether participating in federal food programs is associated with child overweight."

According to Hofferth, substantial federal funds are spent on food programs such as the Food Stamp Program, The National School Lunch Program, the School Breakfast program, the Child and Adult Care Food Program, and Women, Infants and Children (WIC).

"Food programs have received widespread support from the public because they directly benefit children," says Hofferth. "Yet recent media reports have suggested that such programs may have the potential to actually provide too much food to children and, therefore, increase their chance of being overweight. It's important to know if there is a connection, because evidence for that could result in cutbacks in program funds."

The Sample

Hofferth and Curtin examined weight and height, calculating Body Mass Index (BMI) scores, of 1,268 children between the ages of 6 and 12. A number of these children participated in federally subsidized school lunch or breakfast programs, either for free or for a reduced or subsidized price. The sample included children from high income groups, many of whom regularly bought a subsidized school meal.

Unlike previous studies which defined a broad range of families as low income, the Maryland researchers defined five family income categories: poor, near-poor, working class, moderate income and high income.

"Low income is the major factor determining eligibility for food programs," says Hofferth. "It's important to take level of income into account when we examine the effects of programs, or we could falsely attribute effects to food programs that simply result from low income. In addition, it is important to separate children in families with income under the poverty level from those slightly above the poverty line."

They focused on the Food Stamp and National School Lunch and School Breakfast programs, the major sources of food supplements for low-income, school-age children. They used data from the 1997 Child Development Supplement to the Panel Study of Income Dynamics, collected by the University of Michigan .

Results

The Maryland researchers found that, unlike adults in the lowest income group, children in the poorest families are actually less likely to be overweight and have lower BMI's than most other children. Children from high income families were also less likely to be overweight.

In contrast, the study found that children from families with incomes just over the poverty line -- the near poor-- are the ones most at risk of being overweight and having the highest BMI. "In addition to school food programs, these children in near poor or working class families may have more money to spend on food in school vending machines or the snack bar," says Hofferth.

The study also found:

• Poor children benefit substantially from food programs. The BMI levels of children from the poorest families who didn't eat a school lunch were below the average for all children, whereas the BMI levels were about average for those who ate a school lunch. The extra food provided by food programs helps low-income children to maintain a normal body weight.
• School lunch participation was not the determining factor in a child's being overweight. "At first, it looked as though our results indicated that children had a greater chance of being overweight if they ate school lunches," says Hofferth. "But when we adjusted for differential preferences of overweight and nonoverweight children for eating a school lunch, the school lunch impact disappeared. It's more a matter of food choice -- children who are overweight are more likely to eat a hot lunch at school than non-overweight children."
• Black and Hispanic children were more likely to eat a hot school lunch, as were children with a parent who had completed less than high school, and children living with two parents who were not employed or where only the wife had a job. "All these factors suggest greater financial need," says Hofferth.
• Results suggest that frequent eating out may lead to greater child overweight. The more money a family spent eating out, the higher the children's BMIs.
• It appears that the quantity of food purchased increases with income up to a certain point, and that in high income families, more food expenditure most likely leads to higher quality rather than quantity. Says Hofferth, "That makes food programs slightly more risky for children whose near-poor families may still be eligible for food programs but have more income to purchase food."

"The study results also suggest that generalizing from adult samples to children regarding food intake, nutrition, and overweight is not good practice," says Hofferth. "The effects of programs on children should be studied separately from their effects on adults."

Hofferth's research was supported by a grant from the National Institute of Child Health and Human Development.

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For a copy of the study or more information, contact Sandra Hofferth: (301) 405-8501, hofferth@umd.edu

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