Although this is a seemingly small difference, these adolescents are getting four to 12 minutes of vigorous activity daily and this type of activity burns a lot of energy, Patrick said.

He noted that the findings illustrate a particular need for increased exercise by all girls and improved interventions with Hispanic girls that takes into account social and cultural aspects that may impact weight.

Recruiting adolescents from the practices of 45 primary care physicians in six San Diego County clinics, the investigators found that 45.7 percent of the 878 children were either at risk for becoming overweight, or were already classified as overweight by the standard body mass index (BMI) for age. The sample was diverse with approximately 42 percent of participants from ethnic backgrounds, primarily Hispanic.

Using a combination of measurement tools and adolescent self-reports for dietary and sedentary behaviors, the researchers compiled data on minutes of physical activity per day, hours of television per day, percentage of calories from total fat, percentage of calories from saturated fat, and amount of fiber (grams per day).

The researchers noted that limitations of their study included its restriction to one geographic region, the use of self-report for dietary and sedentary behaviors, and a relatively narrow age range.

Nonetheless, the findings from the study contribute to the body of evidence suggesting that adolescents continue to require interventions that target multiple aspects of physical activity and nutrition, the authors said in their report.