Spontaneous meal patterns of humans: influence of the presence of other people.

Social influences on eating were investigated by paying 63 adult humans to maintain 7-d diaries of everything they ingested, time, subjective hunger, and number of people present. Meals eaten with others contained more carbohydrate, fat, protein, and total calories; had smaller deprivation ratios; and had larger satiety ratios than meals eaten alone. The number of people present was positively correlated with meal size even when meals eaten alone were excluded. Adding the number of people present as a factor in a multiple-regression prediction of meal size more than doubled the variance accounted for, without altering the influence of other predictors, suggesting that social factors are associated independently with an increase in meal size. Meal size was positively correlated with the postmeal interval for meals eaten alone but not for meals eaten with other people. This suggests that social factors increase amounts eaten and disrupt postprandial regulation.