"The childhood obesity epidemic is clearly related to the extra calories kids are consuming today during snacktime," says Barry Popkin, Ph.D., professor of nutrition at the University of North Carolina School of Public Health. Even worse, experts say, this trend spans the ages -- from toddlers to teenagers.
Trouble is, these days kids aren't only snacking more often, but when they do, they also take in much bigger portions and more fattening foods and drinks. As a result, American children are consuming more calories between meals than they ever have.
Take a typical snack for a toddler: A small box of animal crackers and a 6.75-ounce juice box have some 350 calories -- about a third of the calories a 2-year-old needs in an entire day. Which adds up. On average, the typical American 2-year-old consumes about 1,250 calories a day. But he needs only 1,000.
A generation ago, says Popkin, kids got less than 20 percent of their daily calories from snacks. Today, it's about 25 percent -- and rising.
And when toddlers and preschoolers snack too often -- and on the wrong foods -- they're setting the stage for a lifetime struggle with their weight, and their health. "The roots of childhood obesity take hold between the ages of one and five," says William Klish, M.D., a pediatric gastroenterologist at Texas Children's Hospital in Houston.
Of course, babies are naturally chubby. But once a child starts toddling, by about his first birthday, he should slowly lose body fat and gain lean body tissue (mostly muscle) over the course of the next several years. When that doesn't happen, a dangerous cycle is set in motion. If a preschooler is allowed to become overweight, he'll develop too much body fat and won't accumulate as much lean body mass as he needs.
Without enough lean body mass, his metabolism will stall, and he won't burn as many calories, and as much fat, as he should. That, in turn, makes it physiologically easier for him to gain even more weight. The result? "In grade school he'll put on body fat more rapidly than other kids," says Dr. Klish. "If we let toddlers and preschoolers become overweight, on the whole we're condemning them to obesity in grade school and beyond."
Because here's the reality: Overweight kids tend to grow up to be overweight adults.
Robert A. Barnett, Parenting's health editor, is the dad of a 9-year-old girl and the author of several books on food and nutrition.