Portion size normality and additional within-meal food intake: two crossover laboratory experiments

Area of Science:

• Behavioral Nutrition
• Dietary Intake Research

Background:

• Portion size is a key factor influencing food consumption.
• Understanding consumer responses to reduced portion sizes is crucial for dietary interventions.

Purpose of the Study:

• To investigate whether reducing served portion sizes leads to compensatory eating of other foods.
• To determine if the perceived 'normality' of a portion size influences subsequent food intake.

Main Methods:

• Two crossover experiments involving adult participants (n=45 and n=37).
• Participants were served lunchtime portions varying in size, categorized as 'large-normal', 'small-normal', and 'smaller than normal'.
• Participants could serve themselves additional food or dessert, and total meal intake was measured.

Main Results:

• A small but significant increase in additional intake was observed when portions were 'smaller than normal' compared to 'small-normal'.
• No significant difference in additional intake was found between 'small-normal' and 'large-normal' portions.
• All smaller portion sizes were associated with a significant reduction in total meal energy intake.

Conclusions:

• Reducing portion sizes to a 'normal' perceived size may limit compensatory eating.
• Further research is needed to confirm these findings on portion control and energy intake.