Active Voice: Television Viewing Linked to Greater Intra-Abdominal Fat — Independent of Physical Activity and Body Mass Index
By Kara M. Whitaker, M.P.H., Ph.D., and Mark A. Pereira, M.P.H., Ph.D.
Kara M. Whitaker, M.P.H., Ph.D., is a postdoctoral fellow in cardiovascular disease epidemiology and prevention at the University of Minnesota in Minneapolis. She received her Ph.D. and M.P.H. in exercise science from the Arnold School of Public Health at the University of South Carolina in Columbia. Dr. Whitaker’s research examines the effects of physical activity and sedentary behaviors on cardiometabolic risk factors. She has been a member of ACSM since 2011.
Mark A. Pereira, M.P.H., Ph.D., is a professor in the Division of Epidemiology and Community Health at the University of Minnesota in Minneapolis. He received his Ph.D. and M.P.H. in epidemiology from the University of Pittsburgh in Pennsylvania. Dr. Pereira’s research interests include nutritional and physical activity epidemiology, and behavioral interventions to reduce sedentary behaviors.
This commentary presents Dr. Whitaker’s and Dr. Pereira’s views on the topic of a research article that they had published with their colleagues in the March 2017 issue of Medicine & Science in Sports & Exercise® (MSSE).
Over time, our society has become increasingly sedentary as technological advances reduce the need for physical activity. Yet, individuals who engage in high levels of sedentary behaviors (e.g., sitting or lying down) are at increased risk for many adverse health outcomes, including cardiovascular disease, diabetes, cancer and premature mortality. It is concerning that this relationship between sedentary behaviors and chronic disease risk appears to persist even among those who meet the physical activity guidelines. One potential pathway through which sedentary behaviors may independently predict chronic disease progression is body composition, particularly the amount of intra-abdominal fat.
Intra-abdominal fat, i.e., visceral fat, is located within the abdominal cavity and surrounds the organs. This type of fat differs from subcutaneous fat, which is located directly below the skin. A growing body of evidence suggests that visceral fat is a central driver of the health risks associated with obesity. Researchers have found that excess visceral fat is a stronger predictor of cardiovascular and metabolic disease risk, as compared to overall body fat. Physical activity is related to lower levels of visceral fat; however, less is known about the relationship between sedentary behaviors and visceral fat.
In our study, as reported in the March 2017 issue of MSSE, we examined the relationship between six unique sedentary behaviors and visceral fat. For the analyses, we used data from 3,010 black and white adults from the Coronary Artery Risk Development in Young Adults (CARDIA) study. The six self-reported sedentary behaviors included: (1) watching television; (2) using the computer; (3) doing paperwork; (4) listening to music, reading or doing arts and crafts; (5) talking on the phone or texting; and (6) sitting in a car, bus, train or other mode of transportation. Visceral fat was assessed using computed tomography (CT) scans.
We observed a positive association between time spent watching television and visceral fat, independent of total physical activity level, subcutaneous fat, body mass index and other potential confounders. Specifically, we found that for each additional 1.5 hours of television watched, visceral fat was greater by 3.5 cubic centimeters, even among those who were physically active and had a normal body weight. No other sedentary behaviors were associated with visceral fat.
These findings suggest that television viewing may have a unique and independent influence on visceral fat. It is possible that television viewing may be associated with visceral fat, more so than other sedentary behaviors, for many reasons. Some of these include: (1) television viewing time may be easier to recall relative to the other behaviors (reducing measurement error); (2) people may be less prone to engaging in intermittent light physical activity, ‘fidgeting’ and postural changes, while watching TV relative to other behaviors; and (3) food advertisements on television are ubiquitous and likely influence overindulgence in energy dense/nutrient poor food and beverages.
Thus, we conclude that interventions designed to reduce visceral fat may be more effective if the target for behavior change is a reduction in television viewing.