Short-term changes in energy intake and serum insulin, neutral amino acids, and urinary catecholamine excretion in women.

The effect of short-term undereating (4.2 MJ [1000 kcal] for 4 d) followed by overeating (12.6 MJ [3000 kcal] for 2 d) on fasting and 2-h postprandial serum glucose, insulin, and neutral amino acids and on urinary free and total norepinephrine and dopamine excretion was studied in 12 normal women. Protein and sodium intake was constant throughout the study. Serum glucose concentration was not affected by diet but the serum total neutral amino acids (ie, sum of valine, leucine, isoleucine, and phenylalanine) tended to increase during undereating and decrease during overeating. Serum tryptophan concentration, relative to the remaining neutral amino acids, was consequently lower during undereating than overeating. The postprandial increase in serum insulin level was greater during overeating than undereating. Urinary free norepinephrine and total dopamine levels were also increased during overeating, suggesting both sympathetic and dopaminergic activation during overeating after undereating.