There are at least three possible explanations for the lack of a consistent relationship between television viewing and physical activity. The most likely explanation is that the relationship between television viewing and obesity is only partly mediated by reductions in physical activity (Robinson, 1998). Television viewing has been shown to be associated with food consumption (Coon et al., 2001; Jeffery and French, 1998). Children and adults may not only be eating while watching television, but their food consumption may be influenced by the advertising (Gorn and Goldberg, 1982; Jeffrey et al., 1982; Taras and Gage, 1995). A second possibility is that television viewing substitutes for moderate or low-level activities that are difficult to measure, and television viewing is less often substituted for the vigorous activities that are more often and more accurately measured. Finally, television is just one form of sedentary activity and may not serve equally across ages, races, or cultural groups as a proxy for inactivity. Other forms of sedentary behavior in both women and preschool children, aside from television viewing, have not been well characterized.
In summary, while television viewing may be a particular form of inactivity that contributes to overweight and obesity both by reducing energy expenditure and increasing energy intake, the exact mechanism is uncertain. While television viewing may be a plausible target behavior for physical activity, more needs to be known about whether altering television viewing levels in the populations served by WIC would have a demonstrable impact on activity or fatness.
Behavioral indicators of food intake or physical activity hold no promise of distinguishing individuals who are ineligible from those eligible for WIC based on the criterion failure to meet Dietary Guidelines, or on nutrient intake or level of physical activity. However, assessment methods and behavioral indicators do offer promise of improving the understanding of diet and activity behaviors of WIC participants as a group, which could be used to design effective nutrition education programs that target behavior change related to the Dietary Guidelines. Likewise, behavioral indicators hold promise for monitoring the dietary intake and physical activity levels of groups and thereby evaluation of program effectiveness. Research efforts should focus on determining the feasibility and validity of assessing target behavioral indicators for diet and physical activity in the population served by WIC.