Fast-food consumption linked to lower test score gains in 8th
The amount of fast food children eat may be linked to how well
they do in school, a new nationwide study suggests
Researchers found that the more frequently children reported
eating fast food in fifth grade, the lower their growth in reading, math, and
science test scores by the time they reached eighth grade.
Students who ate the most fast food had test score gains that
were up to about 20 percent lower than those who didn’t eat any fast food, said
Kelly Purtell, lead author of the study and assistant professor of human
sciences at The Ohio State University.
“There’s a lot of evidence that fast-food consumption is
linked to childhood obesity, but the problems don’t end there,” Purtell
said. “Relying too much on fast food could hurt how well children do in
The results remained even after the researchers took into
account a wide variety of other factors that may have explained why those with
high fast-food consumption might have lower test scores, including how much
they exercised, how much television they watched, what other food they ate,
their family’s socioeconomic status and characteristics of their neighborhood
“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.
Purtell conducted the study with Elizabeth Gershoff, associate
professor of human ecology at the University of Texas at Austin. The results
are published online in the journal Clinical Pediatrics.
Data from the study came from the Early Childhood Longitudinal
Study-Kindergarten Cohort, a nationally representative study of students who
were in kindergarten in the 1998-1999 school year. It was collected by the
National Center for Educational Statistics.
This study included about 11,740 students. They were tested in
reading/literacy, mathematics and science in both fifth and eighth grades. They
also completed a food consumption questionnaire in fifth grade.
“Fast-food consumption was quite high in these
students,” Purtell said.
Less than a third (29 percent) of the children did not have any
fast food during the week before they completed the questionnaire. But 10
percent reported having fast food every day while another 10 percent ate it
four to six times a week. Slightly more than half of the children ate fast food
one to three times in the previous week.
Children who ate fast food four to six times per week or every
day showed significantly lower gains in all three achievement areas compared to
children who did not eat any fast food the week before the survey.
However, children who ate fast food just one to three times a
week had lower academic growth compared to non-eaters in only one subject,
“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.
Purtell emphasized that this study cannot prove that fast-food
consumption caused the lower academic growth observed in this study. However,
by controlling for other possible explanations for this link, such as family
background and what other food they ate, and by looking at change in
achievement scores, the authors are confident fast food is explaining some of
the difference in achievement gains over time.
In addition, because the study examined only changes in test
scores between fifth and eighth grade it controls for all the early childhood
factors that may affect test grades.
This study can’t say why fast-food consumption is linked to
lower grades, she said. But other studies have shown that fast food lacks
certain nutrients, especially iron, that help cognitive development. In
addition, diets high in fat and sugar — similar to fast-food meals — have
been shown to hurt immediate memory and learning processes.