Physiological, environmental, and subjective determinants of food intake in humans: a meal pattern analysis.

The spontaneous food intake of 31 adult humans was investigated with diary self-reports of ingestive behaviors and subjective hunger over 7 consecutive days. Meals were identified, using five different definitions, and their composition of total calories, carbohydrate, fat, and protein was estimated from a computer file of the nutritive value of foods. These data were analyzed by intercorrelating meal sizes with intermeal intervals, estimated stomach contents and self-reported hunger with univariate and multiple correlation techniques. Human feeding was found to be regulated on the basis of preprandial factors; the premeal interval, estimated premeal stomach content, and self-reported hunger significantly correlating with the meal size. These correlations were significant regardless of whether the meal was evaluated as spontaneous or constrained by external factors, but were stronger when the meals occurred without other people being present. The postprandial relationship between the meal size and the duration of the postmeal interval, which is present in nonhuman species, was only present in humans when meals that were eaten alone were considered separately. This suggests that the species differences may be due to the social context of observation. The intake of carbohydrate, fat, and protein was found to have a suppressive effect on subsequent intake and subjective hunger through their contributions to total food energy ingested. Protein, however, was found to suppress subsequent intake and subjective hunger independent of its contribution to total calories, suggesting that the macronutrients have differing satiating properties.(ABSTRACT TRUNCATED AT 250 WORDS)