SDSU-UCSD Study Ties Lack of Strenuous Exercise, Dietary Fiber to Increased Risk of Adolescent Obesity

A study by researchers at San Diego State University, in collaboration with colleagues at University of California, San Diego, has found that a lack of vigorous physical activity is the main contributor to obesity in children ages 11 to 15, and that fiber intake – not fat calories – was most closely related to an individual’s weight among dietary factors.

The investigators, from SDSU’s Psychology Department and Student Health Services, as well as UCSD’s School of Medicine and Kaiser Permanente San Diego, looked at how nutritional factors, physical activity and sedentary behavior correlated to obesity in 878 adolescents. The study, published in the April 2004 issue of the American Medical Association’s Archives of Pediatric and Adolescent Medicine, is one of the largest and best-conducted efforts ever to probe the relationship between multiple lifestyle factors and obesity in youths, researchers said.

"We’re connecting more dots, and in more detail," said SDSU Psychology professor James Sallis, Ph.D., one of the co-principal investigators for the study along with Karen Calfas, Ph.D., Director of Health Promotion for SDSU’s Student Health Services. (UCSD Professor of Family and Preventive Medicine Kevin Patrick, M.D., served as the study’s principal investigator.) "We’re seeing patterns of behavior that put adolescents at greater risk for being overweight. This promises to improve our ability to advise kids on how they can avoid or reduce obesity -- how to eat better, reducing sedentary time, what kinds of physical activity they should pursue."

The study also found, consistent with previous studies, that overweight status among boys was related to time watching television. Boys in the at-risk or overweight group said they watched 30 percent more minutes of television per non-school day than "normal" weight boys (141.5 minutes vs. 108.4 minutes, respectively). No group difference was found among girls.

In analyzing physical activity, researchers used an accelerometer, a small device worn on a belt that tracks amount and level of all exercise every minute for a week. Both girls and boys in the "normal" weight group participated in two to four more minutes per day of strenuous physical activity compared to those in the at-risk or overweight group – small differences that add up to thousands of calories over a year. Boys, but not girls, also showed a statistical difference between groups in terms of moderate physical activity per day.

The activity data also point to the need for increased exercise among all girls, and that Hispanic girls may need improved interventions that account for specific social and cultural factors that may relate to weight, the researchers said.

In analyzing dietary factors, there was no significant difference in fat calories consumed between the "normal" weight group of adolescents and the at-risk or overweight group. However, the "normal" weight boys and girls consistently reported eating higher amounts of fibrous foods, such as whole grains or fruits and vegetables, in comparison to the at-risk or overweight group.

"This shows the need to go beyond strictly counting calories and look at quality of calories or foods consumed to reduce risks of obesity," SDSU’s Sallis said.

Overall, the investigators found that 45.7 percent of the study’s 878 adolescents were at risk for becoming overweight or were already overweight, according to the standard body mass index (BMI) for age. The children were recruited from the practices of 45 primary care physicians from six San Diego County clinics. Approximately 42 percent of the sample’s participants were from non-white ethnic backgrounds, primarily Hispanic. The study began in 2001 and was funded by the National Cancer Institute.

In addition to Patrick, Sallis and Calfas, study authors included Gregory J Norman, Ph.D., and Marion F. Zabinski, Ph.D., MPH, UCSD; and John Cella, M.D., Kaiser Permanente Medical Group, San Diego.

Sallis said the next phase of this project, gathering data on the effectiveness of various kinds of behavior change strategies (increased activity, changed diet, etc.) on the same group of 878 youths, is under way. That research could be ready for publication as early as mid-2005.

Participants Sought for "Men in Motion" Study
Men between the ages of 25 and 55 are sought by researchers at SDSU and the UCSD School of Medicine to participate in a two-year study designed to help men lose weight, become more physically active, and improve their dietary habits. Sponsored by the National Institutes of Health, the study is called "PACE: Men in Motion."

The program is Internet-based and allows participants to access a website available 24 hours a day, seven days a week. "PACE: Men in Motion" consists of two different groups: Program A will focus on physical activity and nutrition, while Program B includes comprehensive education on various men's health issues, plus activity and diet. Volunteers will be randomly assigned to either Program A or B and will receive financial compensation for their participation.

For more information and to enroll in the study, call the PACE office at (858) 457-7282 or visit the Men in Motion website at http://www.men-in-motion.org.

Media Contact: Jason Foster, SDSU Marketing & Communications, (619) 594-2585, foster@mail.sdsu.edu