Relationship between Meal Size and Frequency and Plasma Insulin Response in Man

The effect of varying the size of a meal on plasma insulin was determined in eight normal male adults. The effect of consuming one half of a meal at 0 time and one half at two hours later was also studied. Each subject was studied on four days, one day when he consumed a whole meal (580 calories) of natural foodstuffs; one day, one-half the meal; one day, one quarter of the meal, and one day when he consumed one half the meal at 0 time and the remainder two hours later. When fractions of the meals were ingested, all ingredients were decreased proportionately. As meal size was increased, a log-dose relationship was observed to characterize the comparison of meal size ingested to plasma insulin response. When on the fourth day the subjects consumed the meal in fractions, the mean sum of the plasma insulin responses was identical to that observed when the meal was eaten at one time. The results suggest that over a four-hour period, the plasma insulin response is a function of the magnitude of the load of calories requiring disposition and that the response does not appear to be influenced by the frequency with which the calories are ingested.