Junk foods high in sugar are prevalent in the United States, and account for about 16 percent of total energy intake. A 2006 review of 30 studies in "The American Journal of Clinical Nutrition" found that consumption of sugar-sweetened beverages was associated with weight gain and obesity. This may be due to the fact that calorie intake from sweetened beverages has increased by 74 calories per day from 1962 to 2000, contributing to positive energy balance and weight gain.