Junk foods make up nearly one third of the calories in the diets of people in the United States, according to a study by the University of California, Berkeley. Gladys Block, a professor of epidemiology and public health nutrition at the university, said: "We know people are eating a lot of junk food, but to have almost one-third of Americans' calories coming from those categories is a shocker. It's no wonder there's an obesity epidemic in this country. "In contrast, such healthy foods as vegetables and fruit make up only 10 percent of the caloric intake in the U.S. diet. A large proportion of Americans are undernourished in terms of vitamins and minerals."