The Determination of Energy Needs

Work by Voit and his associates continued so that by 1900 standard values for heats of combustion of different foods had emerged (Table 1). Respiratory quotients (RQ) were also derived, associated with the utilization of the different foods. The RQ is the molar ratio of the amount of carbon dioxide produced in the oxidation of a substance to the amount of oxygen needed for that oxidation. For carbohydrate the RQ is 1  

C6H1206 + 602 = 6C02 + 6H20 For fatty acids, the RQ is about 0.7  

In the post-absorptive state with the subject at rest not less than 12 h after the last meal, protein catabolism has been completed. An RQ 

Defined sources of food were therefore required. By 1905-1906 diets consisting solely of purified protein, carbohydrate and fat were shown to be inadequate to sustain life. Lunin (1881) and Pekelharing (1905) established that white mice fed a bread baked with casein, albumin, rice-flour, lard, and a mixture of all the salts which ought to be found in their food, with water to drink, starve to death. For the first few days all is well, the diet is eaten, and the animals look healthy. But they all get thinner, their appetite diminishes, and in four weeks all are dead. If however, instead of water they are given milk to drink, they are kept in 

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