|Protein-Energy Interactions (International Dietary Energy
Consultative Group - IDECG, 1991, 437 pages)| |Amino acid
oxidation and food intake| The manner in which nitrogen balances
vary as a function of protein-N intake in adults is illustrated
in the upper panel of Figure 1. Three typical conditions are
represented: (A) When common foods are consumed, so that dietary
protein is accompanied by carbohydrates and fats to the tune of
about 150 kcal/g protein-N (i.e., 17% of dietary energy as
protein). When no food is consumed, urinary nitrogen excretion
is shown here to be about 10 g/d; this amount varies somewhat,
depending in particular on the length of the fasting period. (B)
When foods high in carbohydrate, but containing essentially no
protein, are consumed in amounts sufficient to cover daily
energy needs (i.e., - 1500 kcal/d), nitrogen losses are reduced
to some 5 g N/d. This corresponds to the minimal or 'obligatory
N loss'. Consumption of increasing amounts of protein in
addition to the protein-free fo