Increasing the portion size of a sandwich increases energy intake

Objective This study investigated the effect on energy intake of increasing the portion size of a food served as a discrete unit. Design A within-subject design with repeated measures was used. Subjects/setting The sample comprised 75 young adults (37 females and 38 males) from a university community. Intervention Individuals ate lunch in the lab once a week for 4 weeks. Each week, they were served one of four sizes of a deli-style sandwich (6, 8, 10, or 12 inches), of which they could eat as much as they wanted. Main outcome measures Energy intakes were determined for each meal, as were ratings of hunger and satiety before and after each meal. Statistical analyses performed A linear mixed model with repeated measures was used. The influence of subject characteristics was examined using analysis of covariance. Results The portion size of the sandwich significantly influenced lunch intake for both males and females (P<.0001). The majority of individuals consumed the entire 6-inch sandwich. When served the 12-inch sandwich, compared with the 8-inch sandwich, females consumed 12% more energy (74 kcal) and males consumed 23% more energy (186 kcal). Despite these differences, ratings of hunger and fullness were not significantly different after eating the 12-inch and 8-inch sandwiches. Applications/conclusions These results suggest that increasing the portion size of a food served as a discrete unit leads to increased energy intake at a single meal without differentially influencing ratings of hunger and satiety. Dietitians should educate their clients about strategies to moderate the effect on intake of increased portions of high-calorie foods.