Smarter youngsters may be less apt to be overweight, a new study hints.

In the study, researchers from Spain found that preschool kids with above average language, number, and puzzle solving skills were less likely to be overweight two years later when they were old enough to enter school.

A growing body of evidence points to a link between being overweight and having poor thinking, or “cognitive” skills. This led Dr. Monica Guxens, at the Center for Research in Environmental Epidemiology in Barcelona, and colleagues, to look for associations between cognitive function and weight in a group of preschool-age boys and girls.

They report, in the American Journal of Epidemiology, that kids functioning at a higher cognitive level at the age of 4 were less likely to be overweight when they were 6 years old.

However, due to the low variability in body weight among the preschool children in this study, the researchers were unable to determine whether higher, early-age thinking skills actually protect a child from being overweight when older.

The investigators used standard cognitive function tests to determine the verbal, number, memory, fine motor (drawing), and gross motor (ball playing) skills of about 400 boys and girls who were 4 years old.

When the children were 4 and 6 years old, they categorized weight using body mass index - the ratio of height to weight commonly used to determine how fat or thin a person is.

By the time the kids turned 6 years old, nearly 17 percent were at risk of becoming overweight, and another 12 percent were overweight, the researchers found.

Compared with kids who were of a healthy weight, Guxens’ team found those who were overweight at age 6 had lower general thinking and verbal skills, on average, when they were 4 years old.

This association remained after allowing for other factors that might influence the results such as gender, weight at birth, characteristics of the mother, number of siblings, and diet.

Moreover, the children with higher thinking and verbal skills at age 4 were less likely to maintain an unhealthy weight status during the subsequent 2 years.

Gluxens’ team calls for additional long-term investigations to further clarify their observations.

SOURCE: American Journal of Epidemiology, August 15, 2009.