Childhood obesity has risen because children are eating more and exercising less. Exactly which foods are responsible is unclear. In this study, information gathered by the US Department of Agriculture between 1909 and 2007 shows that the major contributors are oils, shortening, meat, cheese and frozen desserts. Cheese intake has increased from 1.7 to 14.9kg per year and frozen dairy products increased from 0.7 to 11.5 kg per year. From 1970 to 2007, intake of sweeteners increased from 54 to 62kg per year.
Barnard, 2010. Trends in food availability, 1909-2007. American Journal of Clinical Nutrition. 91(5):1530S-1536S.