I multiplied protein, fat and carbohydrate values by 4-9-4 my energy value is different from USDAs. Why?
Calorie values are based on the Atwater system for determining energy values. The factors used in the calculation of energy in the database are given in the food description file of the USDA National Nutrient Database for Standard Reference, Release. The basis and derivation of these factors are described in Merrill, A.L. and Watt, B.K. 1973. Energy Value of Foods…Basis and Derivation. Agriculture Handbook No. 74. U.S. Government Printing Office. Washington, DC. 105p. This reference is out of print, but a scanned copyis viewable on our home page. It may also be available at many university libraries. The Atwater system uses specific energy factors which have been determined for basic food commodities. These specific factors take into account the physiological availability of the energy from these foods. The more general factors of 4-9-4 were developed from the specific calorie factors determined by Professor Atwater and associates. For multi-ingredient foods which are listed by brand
