Children are impulsive. Any parent knows that from experience they want everything they see, and they want it right now. That's not necessarily a bad thing; grabby curiosity is what spurs kids to explore their world and learn new things.
But that same self-indulgence may also be helping to drive children to obesity. That's the conclusion of a group of researchers who studied the relationship between self-control and weight gain in youngsters enrolled in a government study. In two papers published this week in the Archives of Pediatrics and Adolescent Medicine, scientists found that preschool-age children who had trouble with self-control and the ability to delay gratification gained more weight by the time they were preteens than those who were better at regulating their behavior. (See nine kid foods to avoid.)
It's not a revolutionary finding, but it represents some new thinking among researchers about how to tackle the burgeoning obesity epidemic, particularly among children. In the same journal, the first national survey of childhood obesity to include American-Indian and Asian ethnic groups found that 18% of 4-year-olds in the U.S. are obese, or in the 95th percentile of body-mass index (BMI), a ratio of weight to height. That percentage is almost doubled among American-Indian children, 31% of whom are obese.
"We think a lot about obesity interventions, about prevention and focusing on eating healthy and exercising more," says Dr. Julie Lumeng, a pediatrician at the University of Michigan and an author of one of the current papers on children's behavior and weight. "But all of us, including doctors, are struggling because those interventions are not wildly successful."
The two studies on self-control may explain why. The authors argue that applying well-known theories of child development to improving self-control in kids may help prevent later overeating and weight gain. Both trials analyzed data from the National Institute of Child Health and Human Development's Study of Early Child Care and Youth Development (SECCYD), a long-term study of more than 1,300 children begun in 1989 at 10 sites across the U.S. SECCYD's mission is to unpack the factors that influence child development and behavior, from parenting choices to social and environmental influences. (See pictures of what makes you eat more food.)
In one study, Lori Francis at Penn State University analyzed data collected on 1,000 children who participated in two different self-regulation tasks, one at age 3 and the other at age 5, and were followed until age 12. In the first task, designed to measure self-control, the 3-year-olds were left alone in a room with a bunch of toys one of which was a known favorite for 150 seconds. They were instructed to play with the other toys but not to touch the favored one. Children who were able to wait 75 seconds or longer before touching the favorite plaything were scored by the researchers as having high self-control. Children who went for the forbidden toy within 75 seconds were labeled as having low self-control.
In the second part of the study, Francis' team looked at the same children two years later, at age 5. This time, the kids were tested on whether they could resist temptation and delay gratification from food. Each child was asked to pick a favorite among M&Ms, animal crackers and pretzels and was then placed in a room with two piles of the chosen snack one large pile, one small. Before leaving the room, the experimenter told the children they could eat from the smaller pile at any time, but if they wanted to eat from the larger pile, they had to wait until the experimenter returned. Kids who waited 210 seconds for the researcher to come back scored high on self-control, while those who couldn't wait to eat from the larger snack pile scored low.
Francis found that the children who scored lower on both tasks were 30% heavier by the time they were 12, compared with kids who were better able to control their impulses. Not only did low-scoring kids gain more weight, but they also gained it faster, showing the most rapid increases in BMI over the nine years of the study's follow-up. (Read TIME's 2008 cover story "Our Super-Sized Kids.")
In a second study, Lumeng found a similar association between the inability to delay gratification in 4-year-olds (again with favorite foods) and weight gain by age 11. Of the 805 children in the study, 47% had trouble with self-restraint; those kids were 30% more likely to be overweight seven years later, compared with other children in the study. The findings indicate that learning self-control may be an important way for children to manage their weight a logical theory, familiar to anyone who has struggled with self-discipline and impulse regulation to keep from packing on the pounds. The findings also suggest that treatments for obesity may not be doing enough to encourage responsibility early on among individuals and families. (See pictures of what people around the world eat.)
"There is an emerging understanding that all of the classic concepts in child development have not been brought to bear on the obesity epidemic," says Lumeng. "There needs to be more bringing together of child development and obesity research to find more practical ways of addressing the obesity problem. We can't stay theoretical for much longer."
There are ways to improve children's self-control when it comes to food, such as mindfulness techniques that train kids to stop and think about whether they are hungry before instinctively reaching for snacks. If impulse control is too difficult for kids, say experts, parents can remove temptations by limiting access to favorite treats and restricting eating to preset snack and meal times.
Taken together, these studies highlight the fact that old habits die hard: any efforts to strengthen self-control, not just in eating but in all behaviors, must begin early, researchers say. "I think you can be trained to exhibit more self-control," says Dr. Ari Brown, a fellow of the American Academy of Pediatrics in Austin, Texas. "But it's harder to do, the older you get. As pediatricians, we have the chance to help parents create a lifestyle early on, so you don't have to go through behavior modification or a weight loss program to learn healthier eating habits. I think this information is most important for new parents with infants."