Asked to pick the top two from a list of five possible reasons that people eat so much junk food, respondents most often cited convenience (73%). Other reasons were that it's what people like to eat (44%); it's because of heavy advertising (37%); it's more affordable (24%); and it's because people don't know which foods are healthy (14%). While both heavy and light consumers of junk food agree that convenience is the biggest reason for America's junk food habit, those who say they rarely or never overeat junk food are more likely to stress the importance of advertising as a factor in the consumption of junk food by others. Those who acknowledge that they themselves eat too much junk food are more likely to stress that it's what people like to eat.
Source: Pew Research Center