The extent and time course of caloric compensation for surreptitious dilutions and supplements to the energy value of the diet were examined in free-living normal-weight adults. Ten subjects were provided lunches containing approximately 66% more or less calories than their customary midday meal for 2-wk periods which were interposed between 1-wk baseline or recovery periods. Diet records were kept throughout the study. Total energy intakes did not differ among the three control periods (weeks 1, 4, and 7) or between any of these periods and when subjects were provided the low-calorie meal. Total energy intake was significantly higher relative to all other periods when subjects ingested the high-calorie meal. To the extent that compensation occurred, it was apparent immediately and did not appear to change over the 2-wk study periods. The results suggest that humans compensate more readily for decreases than for increases in caloric intake.