Can serving-size labels reduce the portion-size effect? A pilot study.

Research has shown that the bigger the portion that people are served, the more food they eat; this phenomenon is referred to as the portion-size effect. Providing objective serving-size information on food products has been shown to reduce the influence of external food cues on people's eating behavior. The current study examined whether providing objective serving-size information would also reduce the portion-size effect. 100 female participants were served either a small or large portion of pizza in the context of a taste test. The large portion was either unlabeled, labeled as "Contains 2 servings," or labeled as "Contains 4 servings." Food intake was lower when the large portion was labeled "Contains 4 servings" compared to when it was labeled "Contains 2 servings." Moreover, participants' intake in the large portion/4 servings condition was statistically similar to the intake of participants in the small portion condition. Thus, the standard portion-size effect was observed when the large portion was unlabeled or was labeled as "Contains 2 servings," but not when the large portion was labeled as "Contains 4 servings". These findings suggest that providing serving-size information can reduce the portion-size effect, but that the specific content (and not just the presence) of serving-size information is important in determining food intake.