Sensitivity to portion size of unhealthy foods

• We examine young women’s sensitivity to portion size of unhealthy foods.
• Sensitivity to portion size was strong overall but declined as portions increased.
• Sensitivity varied as a function of unhealthy food type.
• Healthy Food Consumption predicted greater sensitivity to portion size.
• Diminished sensitivity to portion size has implications for excess energy intake.

BackgroundSensitivity to portion size, a less-investigated aspect of portion size perception, refers to individuals’ abilities to distinguish portion sizes of differing amounts.ObjectiveThe aim of this cross-sectional study is to investigate normative and person-specific aspects of sensitivity to portion size via an evaluation of the perceived healthiness of photographed foods that vary as a function of portion size and food type.Participants/setting272 undergraduate women judged the healthiness of 124 unhealthy food stimuli that varied in portion size (small to extra-large) and food type (Sweets, Fried Foods, and Candies).Statistical analysesMultilevel modeling estimated normative sensitivity to portion size, food-specific predictors of participants’ sensitivity, and participant-specific predictors of sensitivity.ResultsParticipants displayed strong sensitivity to the portion size of unhealthy food, overall, but sensitivity declined as portion size increased. Sensitivity varied as a function of unhealthy food type; participants showed reliably greater sensitivity to portion size for Sweets and Fried Foods than for Candies, although sensitivity to all three food types was substantial. Healthy Food Consumption predicted greater portion-size sensitivity for unhealthy foods at a small-to-moderate level (i.e., those who reported consuming more fruits and vegetables showed greater portion-size sensitivity). A parallel analysis of sensitivity to caloric content, rather than portion size, produced highly similar findings.ConclusionsWhen judging food healthiness, college-aged women distinguished well between unhealthy foods with small-to-moderate portion sizes, but their discriminative abilities faltered as portion sizes increased. Healthy Food Consumption was associated with greater sensitivity to portion size for unhealthy food. Future public-health campaigns should highlight the significance of inaccurate portion-size estimation and continue to develop strategies that enhance sensitivity to portion size.