Increased TV viewing time among children and young people is associated with a raisedlikelihood of overweight. This results from a combination of unhealthy dietary habits,sedentary behaviour,and exposure to TV advertising. It also appears that excessive TV viewing among adolescents may lead to poor dietary patterns in later years. Reducing television time can lead to decreases in BMI. TV viewing is a good marker of other factors, which are associated with obesity, although the exact nature and strength of the relationship is unclear. These include parental TV viewing and diet quality, socioeconomic status, number of TVs in the household, presence of a TV in the child's room, and household rules about television viewing.