This study addresses two questions about sub-packaging: (i) Do 100-calorie packages reduce the calorie intake of overweight individuals differently than normal-weight individuals? (ii) Do they enable individuals to accurately track intake? Thirty-seven undergraduates were randomly given either four 100-calorie packages of crackers or one 400-calorie package of crackers to eat while watching television. The average participant ate 25.2% (75.1 calories) less when given four 100-calorie packages of crackers than when given one 400-calorie package (P = 0.006). In addition, much of this influence was driven by overweight participants whose intake decreased by 54.1%. However, all of the participants underestimated their consumption by 60% or more, indicating that sub-packaging does not appear to increase one's accuracy in estimating how much is consumed. Smaller sized sub-packaging most greatly benefits those who are overweight, yet it does so without making people more aware of how much they have eaten.