The Effect of Television Watching and Portion Size on Intake During a Meal

Background: Several investigations have examined the influence of television and portion size on intake. Results have found that watching television while eating or being provided larger portions increases intake. However, no investigation has examined the combined effect of these variables on food intake, when these factors are combined they may enhance consumption.

Methods: To test the influence of television and portion size on intake during a meal in healthy weight adults, a 4X2X2 mixed factorial design was used, with a between-subject factor of order of conditions and within-subject factors of television (TV vs. NO TV) and portion size (SMALL vs. LARGE). Seventeen women and three men (21.6 + 2.3 kg/m², 22.3 + 3.7 years), who were predominately white (80%), and non-Hispanic (95%), were randomized to one of four orders of conditions. For TV conditions, participants viewed a 30-minute show (no commercials or food cues), for NO TV conditions participants sat for 30 minutes. Participants received 500g macaroni and cheese (998 kcal) and 150g salad with dressing (85 kcal), providing a total of 1083 kcal in SMALL conditions; while LARGE conditions were provided with portions 200% of SMALL conditions. Dependent variables were grams and energy consumed during the meal.

Results: Factorial ANOVA revealed a significant main effect of portion size on grams and energy consumed of the total meal. Participants consumed more grams (577.9 + 150.5g vs. 453.1 + 96.6g; p<0.046) and more energy (903.9 + 270.4 kcal vs. 734.6 + 187.1 kcal; p<0.049) when provided a larger portion size. Factorial ANOVA revealed a significant main effect of food type for grams and energy consumed. Participants consumed more grams (368.9 + 114.1g vs. 146.7 + 44.7g; p<0.006) and more energy (736.2 + 227.8 kcal vs. 83.0 + 25.3 kcal; p<0.000) of macaroni and cheese as compared to salad with dressing. A significant main effect of television viewing or interaction of television viewing x portion size was not found.

Conclusion: Watching television did not increase intake during a meal. Greater gram and energy intake occurred when larger portion sizes were provided. To assist with reducing intake, smaller portion sizes should be implemented.