title: Increasing the size of portion options affects intake but not portion selection at a meal.
abstract: In an environment with large portion sizes, allowing consumers more control over their portion selection could moderate the effects on energy intake. We tested whether having subjects choose a portion from several options influenced the amount selected or consumed when all portion sizes were systematically increased. In a crossover design, 24 women and 26 men ate lunch in the lab once a week for 3 weeks. At each meal, subjects chose a portion of macaroni and cheese from a set of 3 portion options and consumed it ad libitum. Across 3 conditions, portion sizes in the set were increased; the order of the conditions was counterbalanced across subjects. For women the portion sets by weight (g) were 300/375/450, 375/450/525, and 450/525/600; for men the portions were 33% larger. The results showed that increasing the size of available portions did not significantly affect the relative size selected; across all portion sets, subjects chose the smallest available portion at 59% of meals, the medium at 27%, and the largest at 15%. The size of portions offered did, however, influence meal intake (P < 0.0001). Mean intake (±SEM) was 16% greater when the largest set was offered (661 ± 34 kcal) than when the medium and smallest sets were offered (both 568 ± 18 kcal). These results suggest that portions are selected in relation to the other available options, and confirm the robust effect of portion size on intake. Although presenting a choice of portions can allow selection of smaller amounts, the sizes offered are a critical determinant of energy intake. Thus, the availability of choices could help to moderate intake if the portions offered are within an appropriate range for energy needs.
authors.affiliation: Department of Nutritional Sciences, The Pennsylvania State University, USA.
authors.forename: Faris M
authors.initials: FM
authors.lastname: Zuraikat
authors.affiliation: Department of Nutritional Sciences, The Pennsylvania State University, USA.
authors.forename: Liane S
authors.initials: LS
authors.lastname: Roe
authors.affiliation: Department of Psychology, Saint Bonaventure University, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Privitera
authors.affiliation: Department of Nutritional Sciences, The Pennsylvania State University, USA. Electronic address: bjr4@psu.edu.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Rolls
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D018592:Cross-Over Studies; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D006815:Hunger; D016015:Logistic Models; D008297:Male; D062407:Meals; D008875:Middle Aged; D064787:Portion Size; D011897:Random Allocation; D012527:Satiation; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Eating environment; Energy intake; Portion selection; Portion size