are multifold. For one, increased TVV increases sedentary behavior which in turn is likely to displace time spent in physical activity.

Second, TVV also provides a setting during which food, especially energy-dense snack foods, can be consumed. A study conducted by Francis et al. [114] showed that TVV viewing was associated with increases snack food consumption in girls who were 5, 7, and 9 years old which in turn predicted girls’ increase in BMI from age 5 to 9. Thus, TVV has been shown to be a risk factor for excessive snack consumption and in turn increased weight status, especially for those individuals who are predisposed for obesity. Another study [115] also demonstrated that physical activity (negatively associated) and TVV (positively associated) were the only significant predictors, beyond baseline BMI, of BMI in children between the ages of 3 and 4 years during a 3-year study phase.

A third mechanism by which increased TVV may lead to increased energy intake may involve the increased exposure to food advertising. A study conducted by Henderson and Kelly [116] was designed to analyze the content of food advertising appearing on either general market or African American TV programming. The results of the study showed that African American TV programs included more food advertisements, more advertisements for unhealthy foods such as fast food, candy, soda, or meat, and made more weight-related claims and those related to the fat content of foods compared to advertisements that appeared in general market television. Thus, food advertisements seem to be targeted at and tailored to specific populations to increase product sales.

In summary, television viewing has been associated with increased energy intake and weight status among individuals. It remains to be further investigated whether TVV is a behavior that, through its association with sedentarianism, may be fostered through an individual’s biology, as the following section on NEAT alludes to.

Nonexercise Activity Thermogenesis (NEAT)

NEAT has been defined as energy expenditure that is associated with daily activities such as sitting, standing, walking, and talking and as such is different from purposeful, planned physical activity [117]. NEAT can further be divided into thermogenesis that is associated with posture (standing, sitting, and lying) and that associated with movement (ambulation). Research conducted by Levine and colleagues [117] has shown that obese individuals, on average, were seated longer per day and spent less time in an upright position, compared to lean individuals. Overall this difference accounted for an additional energy expenditure of 352 calories per day, on average, for lean individuals. Interestingly, the difference in NEAT was not due to the differential body weights of the study participants per se, but

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement