There is a strong link between the amount of fast food that pre-school age children consume and their likelihood of becoming overweight or obese, according to a new Dartmouth-led study, published in the journal Pediatric Obesity.

According to the Centers for Disease Control and Prevention, nearly 25 percent of children between the ages of 2 and 5 years are overweight or obese in the U.S. These conditions increase the risk of numerous physical and psychosocial problems during childhood, including fatty liver disease, type 2 diabetes, and depression.

“We now know from our studies and others, that kids who start on the path of extra weight gain during this really important timeframe tend to carry it forward into adolescence and adulthood, and this sets them up for major health consequences as they get older,” says first author Jennifer Emond, PhD, MS, an assistant professor of biomedical data science and of pediatrics at the Geisel School of Medicine at Dartmouth.

Previous research has shown that fast-food intake is common among children—about one-third of U.S. children consume fast food daily—and has suggested that there is an association between fast food consumption and children becoming overweight or obese. But it hasn’t been clear whether eating fast food independently contributes to excess weight gain at such a young age.

In an effort to make this determination, the investigators followed a cohort of more than 500 pre-school age children (ages 3 to 5) and their families in southern New Hampshire for one year. The height and weight of the children were measured at the beginning and end of the study. Parents reported their children’s fast-food intake frequency weekly—from 11 chain fast-food restaurants—in six online surveys that were completed at two-month intervals.

The researchers found that at the beginning of the study, about 18 percent of the children were overweight and nearly 10 percent were obese. Importantly, about 8 percent of children transitioned to a greater weight status over the one-year period.

“To our knowledge, ours is the first study to follow a cohort over time and to show that fast food, by itself, uniquely contributes to weight gain,” explains Emond. “Unlike with past research, we were able to adjust for other factors—such as exercise and screen time—that could possibly explain away this relationship.

“Findings from this research,” says Emond, “should be used to inform guidelines and policies that can reduce fast-food marketing exposure to children and help support parents who may be struggling to adopt healthier eating behaviors for their kids.”

Founded in 1797, the Geisel School of Medicine at Dartmouth strives to improve the lives of the communities it serves through excellence in learning, discovery, and healing. The Geisel School of Medicine is renowned for its leadership in medical education, healthcare policy and delivery science, biomedical research, global health, and in creating innovations that improve lives worldwide. As one of America’s leading medical schools, Dartmouth’s Geisel School of Medicine is committed to training new generations of diverse leaders who will help solve our most vexing challenges in healthcare.