Is Lack Of Exercise Responsible For Obesity In Children?

Not all obese children are couch potatoes. While lack of exercise can contribute to obesity, it is far from the only factor to do so. In a study published in the official journal of the American College of Sports Medicine in December 2010, researchers from the University of Southern California and the National Institutes of Health found that age, gender, socioeconomic status and race/ethnicity also play roles in a child's obesity risk. In fact, higher levels of physical activity weren't associated with lower levels of obesity, according to the study's lead author Britni Belcher.

Activity Levels

Belcher's study compared white, Mexican-American and black children. White children overall were the least active and black children the most active. But, despite the increased activity, black and Mexican-American children had the highest prevalence of obesity. Across all groups, boys were more active than girls and pre-pubertal children more active than adolescents. Another surprising finding: girls of normal weight were generally less physically active than obese boys.

Socioeconomic Factors

Obesity affects certain ethnic groups disproportionately in the U.S., according to the National Health and Nutrition Examination Survey. While a relationship exists between higher socioeconomic status and lower rates of obesity, this seems true only for white children. African-American, Mexican-American and Native American children with higher socioeconomic status are just as likely to be obese as their lower socioeconomic counterparts, according to NHANES. The underlying factors of less healthy eating patterns and cultural ideas of body weight and image, may also affect the relationship between obesity, ethnicity and socioeconomic status.

The Chicken or the Egg

The EarlyBird Diabetes Study, conducted by researchers from Peninsula Medical School in Plymouth, U.K., studied more than 200 children over an 11-year period. Their findings suggest that it is not lack of activity that causes obesity, but obesity that results in lack of activity. While higher body fat percentage was predictive of a decrease in physical activity over the following three years, more physical activity was not predictive of any decrease in body fat percentage over the same period.

More Than Meets the Eye

The science of nutrigenomics studies the relationship of nutrition on a genome level. "We are not all built the same; we have individual genotypes," says Dr. David Edelson, weight loss and bariatrics expert in Manhasset, New York. The finding that obese children are often the most active does not surprise him; he says it only makes clear how much more is going on in the obesity crisis than we realize. A child's genetic makeup, including age, gender and ethnicity may have as much to do with obesity risk as lack of exercise.