Dietary restraint and self-reported meal sizes: diary studies with differentially informed consent

Area of Science:

• Psychology
• Nutrition Science
• Behavioral Science

Background:

• Dietary restraint is a key factor in eating behavior research.
• Accurate measurement of food intake is crucial for understanding dietary restraint.
• Self-report methods are commonly used but their psychometric properties require validation.

Purpose of the Study:

• To evaluate the reliability and criterion validity of self-reported food intake measures.
• To assess the suitability of aggregate versus individual meal intake data for studying dietary restraint.
• To examine the relationship between dietary restraint and food intake patterns.

Main Methods:

• Two studies utilized psychometric methods and food diaries to assess self-reported food intake.
• Study 1 involved 27 low-BMI females over 7 days; Study 2 involved young males and females with various BMIs over 1 day.
• Reliability (Cronbach's alpha) and criterion validity were analyzed for aggregate daily intake and individual meal sizes.

Main Results:

• Aggregate daily food intake showed poor reliability across both studies.
• Individual meal sizes demonstrated day-to-day consistency but poor correlation with total intake.
• Breakfast intake showed criterion validity in both studies, with complex relationships to restraint; total intake also showed validity in Study 2.

Conclusions:

• Aggregate self-reported food intake measures have low reliability and questionable validity for studying dietary restraint.
• Individual meal data, particularly breakfast, may offer better, though not perfect, criterion validity.
• Researchers should carefully consider the psychometric limitations of self-reported intake data when investigating dietary restraint.