About half of the growth in food-related energy use between 1997 and 2002 is explained by a shift from human labor toward a greater reliance on energy-intensive technologies. High labor costs in the foodservices and food processing industries, combined with household outsourcing of manual food preparation and cleanup efforts through increased consumption of prepared foods and more eating out, appear to be driving this result. Increases in per capita food expenditures (adjusted for inflation) and population growth also helped drive up food-related energy use over this period, with each trend accounting for roughly a quarter of the total increase. Data for 2007 show an 8-percent increase in food-related energy use since 2002. (source: usda)