Biochemical Concomitants of Hunger and Satiety in Man

Abstract

Studies were performed to determine the following: (1) whether a significant correlation could be obtained between diurnal changes in peripheral arteriovenous glucose differences and variation in plasma non-esterified fatty acids (NEFA) in normal subjects on self-selected diets; (2) whether an association might exist between the diurnal changes in plasma NEFA and concurrent experience of hunger or satiety and; (3) whether a similar association could be obtained when meals of altered composition were consumed. Nine subjects consumed their usual self-selected diet and a record was made of what was eaten during breakfast and luncheon. Six of these subjects and one additional subject were changed to a breakfast and luncheon that were free of carbohydrate. One subject, aged seventy-nine, who had voluntarily consumed a carbohydrate-poor diet for five years, was studied during a typical nine hour day. Measurements were made of plasma NEFA and capillary (arterial) and antecubital venous glucose concentrations while the subjects were in the postabsorptive state, and at half to one hour intervals following their meals. In the subjects on self-selected mixed diets, a good correlation was obtained between diurnal changes in arteriovenous glucose differences and NEFA. Appreciable increases in arteriovenous glucose differences were associated with reciprocal changes in NEFA levels. The hunger satiety pattern paralleled the pattern of NEFA change. When the subjects were changed to carbohydrate-poor diets, arteriovenous glucose differences remained negligible throughout the day. The change of pattern of NEFA, however, tended to parallel the hunger satiety pattern. The subject, who was accustomed to a carbohydrate-poor diet, showed a similar response. It is probable that NEFA levels per se do not act directly as a signal to the food regulatory center. However, the pattern of NEFA change may provide a useful index of the physiologic readiness of the body to consume more food.