Using a Visual Cue as Intervention Did Not Reduce the Portion-Size Effect

Abstract

Increased portion sizes leads to increased energy intake, which is associated with obesity. This study examined whether a visual cue as food presentation reduced this portion-size effect. In a 2 by 2 between subject design, 125 participants (84 females, 41 males) were tested to examine the effects of portion size (±40g or ±80g of nachos) and the visual cue of presentation style (in a bowl or circular on a plate). Participants were matched on sex to one of the four conditions: SmallBowl, SmallPlate, LargeBowl, LargePlate. During the test they watched an episode of friends to covertly expose them to the experiment. Results showed a significant effect of portion size (F(1, 114) = 18.75, p = .000 and no effect of presentation and interaction was found (F(1, 114) = .12, p = .73) and F(1, 114) = 1.24, p = .27), respectively). These effects remained significant and insignificant after introducing the covariates hunger and likability of the nachos to the model. On average 53% more nachos were consumed in the large conditions compared to the small conditions. In line with previous research the portion size effect was confirmed in this research. However the intervention of the visual cue had no effect. This suggests that the portion-size effect is strong and future research should address other interventions (for example dividers or colors) to reduce it, to help the prevention and treatment of obesity.