Served Portion Sizes Affect Later Food Intake Through Social Consumption Norms

Area of Science:

• Behavioral Science
• Nutrition Science
• Social Psychology

Background:

• Commercially available food portion sizes have increased significantly.
• Exposure to larger portions can recalibrate perceptions of normal intake and increase consumption.
• Social and personal norms surrounding portion sizes may influence eating behaviors.

Purpose of the Study:

• To investigate the role of social (descriptive and injunctive) and personal portion size norms in the effect of portion size exposure.
• To determine if visual exposure or actual serving of portion sizes impacts consumption.
• To examine the mediating role of perceived norms in portion size effects.

Main Methods:

• Two experiments were conducted involving visual exposure (Study 1) or actual serving (Study 2) of smaller or larger food portions.
• Participants' intended or actual food consumption and perceived portion size norms were assessed after a 24-hour delay.
• Statistical mediation analyses were used to explore the role of perceived norms.

Main Results:

• Visual exposure to portion sizes (Study 1) did not significantly alter intended consumption or perceived norms.
• Participants served smaller portions consumed less food 24 hours later compared to those served larger portions (Study 2).
• The reduction in consumption was mediated by perceived descriptive and injunctive social norms, but not personal norms.

Conclusions:

• Actual serving of smaller food portions, unlike mere visual exposure, can influence future food consumption.
• Perceived social norms regarding portion size are key mediators in this effect.
• Findings suggest that adjusting served portion sizes may be an effective strategy to reduce food intake by altering social norms.