Fast food is cheap, filling and of course, fast. That makes it a lifesaver for some parents. But it's also incredibly unhealthy and now a new nationwide study suggests that eating a lot of it might be linked to kids doing badly in school.
Researchers at the Ohio State University (OSU) and University of Texas, Austin, found that the more frequently children reported eating fast food in fifth grade, the lower their improvement in reading, math, and science test scores by eighth grade.
The difference between the test scores of kids who didn't eat any fast food and those who reported eating a lot was significant: 20%.
"There's a lot of evidence that fast-food consumption is linked to childhood obesity, but the problems don't end there," said Kelly Purtell, lead author of the study and assistant professor of human sciences at (OSU). "Relying too much on fast food could hurt how well children do in the classroom."
While eating a lot of fast food is oftentimes a marker for poverty, and poorer students generally don't do as well on standardized tests for a whole battery of reasons, these results held steady even after researchers took into account other factors, including how much the kids exercised, how much TV they watched, the other food they ate, their family's socioeconomic status and the characteristics of their neighborhood and school.
"We went as far as we could to control for and take into account all the known factors that could be involved in how well children did on these tests," Purtell said.
The results, which are published online in the journal Clinical Pediatrics, used data from the Early Childhood Longitudinal Study-Kindergarten Cohort, a nationally representative study of 11,740 students who started school in the 1998-1999 school year.
The kids were tested in reading/literacy, mathematics and science in fifth as well as eighth grades, and also filled out a food consumption survey in fifth grade. Slightly more than half the kids reported eating fast food between one and three times in the previous week. Almost a third had had no fast food that week, while a full 10% reported having it every single day and 10% four to six times a week.
"We're not saying that parents should never feed their children fast food, but these results suggest fast-food consumption should be limited as much as possible," said Purtell, who added that while her study cannot prove that fast-food consumption caused the lower academic growth, she and her fellow authors are confident fast food explains some of the difference in achievement gains between fifth and eighth grade.
Previous studies have shown that fast food is low in such nutrients as iron that aid in cognitive development, which may explain some of the gap in learning. Moreover, diets high in fat and sugar, both of which fast food tends to have in abundance, have been shown to have a bad effect on immediate memory and learning processes.