UNC scientists find U.S. children snack more now than they did two decades ago

CHAPEL HILL -- Using information from three national surveys, scientists at the University of North Carolina at Chapel Hill have confirmed what a lot of people have suspected -- U.S. children snack more now than they did in the late 1970s.

Their research, the first large systematic study of snacking patterns and trends among children in this country, highlights anew a growing threat to the nation's health, the scientists said. Data from more than 21,000 children ages 2 to 18 were analyzed.

"The average size of snacks and energy per snack remained relatively constant, but since the number of times kids eat between meals increased, the average daily energy intake from snacks grew, and that's not good," said Dr. Barry Popkin. "When compared to regular meals, the snacks provided less calcium, more energy and a higher proportion of energy from fat."

Since snacking is so pervasive among children, adults should emphasize and buy healthy foods such as fruits and vegetables instead of convenience foods high in fat, salt and sugar, said Popkin, professor of nutrition and epidemiology at the UNC schools of public health and medicine.

The Journal of Pediatrics carries a report on the research in its April issue. Besides Popkin, authors are Dr. Anna Maria Siega-Riz, assistant professor of nutrition and of maternal and child health, and Lisa Jahns, a dietitian and doctoral student in nutrition. "Rapid increases over the past three decades in childhood obesity and related complications have led to increased concern over the diets of American children," the three wrote. "Among school-aged children and adolescents, the proportion classified as overweight has grown from 8 percent to 14 percent for children and from 6 percent to 12 percent for adolescents between 1976-80 and 1988-94." The rate of increase in overweight has grown further between 1994 and 1999 in results recently reported by the federal government, Popkin said.

For that reason, and because obesity has been linked to adult-onset diabetes and various cardiovascular problems such as heart attacks and strokes later in life, the scientists wanted to learn whether U.S. children had changed their snacking habits over time. They also wanted to know how the changes might -- or might not -- contribute to the nationwide child obesity epidemic. Information they analyzed came from the 1977-78 Nationwide Food Consumption Survey and both the 1989-91 and 1994-96 Continuing Survey of Food Intake by Individuals.

"Back in the 1970s, some 80 percent of U.S. children snacked daily, and we found that now more than 90 percent do," Popkin said. "A more pronounced change, however, is that their total daily energy intake from snacks has risen from about 18 percent to about 25 percent. Whereas two decades ago they were taking in 450 kilocalories of energy in this way, now they're getting 600 kilocalories." Also, kilocalories per gram -- what nutritionists call "energy density" -- have risen significantly, from 1.35 to 1.54, the scientist said.

"What's important about that is that other researchers have found small increases in energy densities lead to a large increase in total energy," he said. "So not only are children -- and adults -- eating a lot more snacks, but we're also getting more calories because we're eating different kinds of foods that are more energy-dense. That's a bad sign and a clear indication that increased snacking contributes to the overweight increases in the United States."

Higher energy-dense foods do not correspondingly decrease appetites more than healthier foods do, Popkin said. Research his group and others have done showed significant increases in consumption of soft drinks, potato and corn chip and other kinds of salty snacks and simultaneous drops in fruit, vegetable and milk consumption.

"It's not that snacks are bad," he said. "In fact, for preschoolers and children age 10 and under they are very important during the day because their stomachs are small, and they need to keep their energy levels high. It's just the kind of snacks should be switched."

The biggest changes in snacking patterns have occurred during the past decade, the UNC group found. That mirrors the increase in obesity among U.S. children. Earlier decades saw far smaller changes in eating behavior.

Note: Popkin can be reached at (919) 966-1732 and by email at [email protected]

School of Public Health