Multimedia message (by rockcreek)
A study linked the amount of time teens spend watching t.v. to an increased risk of becoming obese. The study explained:
Mechanisms may include the influence of TV commercials on preferences for energy-dense, nutritionally questionable foods and/or eating while distracted by TV.
Another study had similar findings:
Although the length of time to eat a slice of pizza remained stable between viewing conditions, the amount of time before starting another slice was shorter during [television viewing].
For a list of environmental factors that may contribute to obesity, click here.
Source: Flickr / rock_creek