Kids from low-income families are more likely to be obese than wealthier children, research suggests. But the relationship is complex, and scientists are still trying to untangle the links between income and such factors as diet and exercise that contribute to obesity.
New data make those connections even more complicated. Low-income kids—from households earning less than $31,500 for a family of four—got about the same percentage of their calories from fast food as wealthier kids, according to a federal survey of more than 5,000 people, including children of all ages, from the Centers for Disease Control (CDC).
That finding contrasts one popular narrative about the link between income and diet. Poor neighborhoods, the theory goes, are “food deserts” where nutritious meals are scarce and more expensive. So residents rely on fast food and processed meals, both of which deliver loads of cheap calories with limited nutritional value.
According to the CDC survey, about a third of kids ages 2-19 ate fast food on the day before the survey was conducted. Wealthier kids got about 13 percent of their calories from fast food, compared with 11.5 percent for poorer children. And regardless of income, overweight or obese kids didn’t report getting more of their calories from fast food. Instead, proportions were similar for kids no matter their weight, and the differences in the chart below weren’t statistically meaningful.
Other recent research has questioned the notion of food deserts' role in diet and weight. In Los Angeles, for example, little evidence supports the idea that living near junk food outlets increases obesity rates, according to another recent CDC study. The authors speculated that L.A.’s driving culture might render a neighborhood’s food options less important than in other cities, where residents rely on walking or public transit.
The survey, experts say, is yet another data point in an ongoing discussion. "With just a one-day snapshot, it’s hard to really make many inferences with that," says Mary Story, a professor at the Duke Global Health Institute who wasn't involved in the research.
It’s possible that while kids of all income levels eat about the same amount of fast food, those in poor households get less nutritious meals at home. Exercise matters, too. Kids in poor neighborhoods may be less likely to play outside if streets are unsafe, a barrier to activity that middle class families don’t face. It's conceivable that other aspects of growing up poor contribute to metabolic changes that make people vulnerable to weight gain.
"We know that childhood obesity is a problem everywhere and that fast food does contribute to that. But we also know that it is a worse problem in low-income communities," says Yael Lehmann, executive director of the Food Trust, a nonprofit that promotes access to healthy food. "In a way it just opens up more questions for us."