Investigating the causes of childhood obesity, determining what to do about them, and taking appropriate action must address the variables that influence both eating and physical activity. Seemingly straightforward, these variables result from complex interactions across a number of relevant social, economic, cultural, environmental, and policy contexts.

U.S. children live in a society that has changed dramatically in the three decades over which the obesity epidemic has developed. Many of these changes, such as both parents working outside the home, often affect decisions about what children eat, where they eat, how much they eat, and the amount of energy they expend in school and leisure time activities (Ebbeling et al., 2002; Hill et al., 2003).

Other changes, such as the increasing diversity of the population, influence cultural views and marketing patterns. Lifestyle modifications, in part the result of media usage and content together with changes in the physical design of communities, affect adults’ and children’s levels of physical activity. Many of the social and cultural characteristics that the U.S. population has accepted as a normal way of life may collectively contribute to the growing levels of childhood obesity. The broad societal trends that impact weight outcomes are complex and clearly multifactorial. With such societal changes, it is difficult to tease out the quantitative and qualitative role of individual contributing factors. While distinct causal relationships may be difficult to prove, the dramatic rise in childhood obesity prevalence must be viewed within the context of these broad societal changes.

An understanding of these contexts, particularly regarding their potential to be modified and how they may facilitate or impede development of a comprehensive obesity prevention strategy, is therefore essential. This next section provides a useful background to understand the multidimensional nature of the childhood obesity epidemic.

The interrelated areas of family life, ethnic diversity, eating patterns, physical activity, and media use—discussed below—are all aspects of societal change that must be considered. Singly and in concert, the trends in these areas will strongly influence prospects for preventive and corrective measures.

The changing context of American families includes several distinct trends such as the shifting role of women in society, delayed marriage,