Increased portion size leads to increased energy intake in a restaurant meal

Objective: Eating frequently in restaurants is one of the behaviors associated with obesity. This study examined whether increasing the portion size of an entree affected energy intake at a restaurant meal. Research Methods and Procedures: In a cafeteria-style restaurant on different days, the size of a pasta entree was varied from a standard portion (248 g) to a large portion (377 g). The entree price was not changed. Intake of the entree was determined by covertly weighing each dish before and after the meal; intake of all other foods was determined by estimating the percent consumed. The 180 adult customers who purchased the entree also completed a survey in which they rated characteristics of the meal, including the appropriateness of the entree portion size and the amount that they ate compared with their usual meal. Results: Portion size had a significant effect on intake of the entree (p < 0.0001). Compared with customers who purchased the standard portion, those who purchased the larger portion increased their energy intake of the entree by 43% (719 kJ; 172 kcal) and of the entire meal by 25% (664 kJ; 159 kcal). There was no difference between the two groups of customers in ratings of the appropriateness of the portion size or of the amount that was eaten in relation to their usual meal. Discussion: In a restaurant setting, increasing the size of an entree results in increased energy intake. These results support the suggestion that large restaurant portions may be contributing to the obesity epidemic.