It has often been proposed that young (three to six years old) children's television viewing habits contribute to early-onset obesity. Three explanations that link television viewing patterns of young children with the development of obesity are considered. First, television viewing displaces time available for physical activity, reduces energy expenditure relative to energy intake and leads to obesity. Second, the cognitive immaturity of young children increases their susceptibility to persuasive intent of advertisements for foods of poor nutritional quality. Such food advertisements are broadcast often during children's television programmes and lead to unhealthy food preferences, and dietary imbalances associated with obesity. Third, activity displacement combined with susceptibility to persuasive intent of televised food advertisements predispose young children to early-onset obesity. Research evidence in support of each explanation is questionable, because of conceptual and methodological shortfalls in existing research. How future research might address shortfalls is considered.