Self-reported dieting: how should we ask? What does it mean? Associations between dieting and reported energy intake.

OBJECTIVES

To determine whether self-reports of dieting to control weight are associated with reported energy intake, how this association varies with the phrasing of questions on dieting behaviors, and whether this association differs by educational level and weight status among adult male and female respondents.

METHODS

The study population included 996 women and 227 men, aged 20-45, who volunteered to participate in a weight gain prevention trial. Participants completed surveys at baseline regarding their dieting behaviors and nutritional intake.

RESULTS

The association between self-reported dieting and energy intake varied according to the phrasing of the questions assessing dieting behaviors. Multi-item scales and nonambiguous single-item questions (e.g., "current dieting") were more strongly associated with reported energy intake than more general single-item questions (e.g., "doing anything to lose weight"). Overweight dieters reported lower energy intake than overweight nondieters. Among nonoverweight persons, associations between dieting and energy intake were not significant. The association between dieting and energy intake did not differ by educational level among women. Among men, dieting predicted lower energy intake in those with low educational levels, although the number of men with low educational levels who were dieting was small. Reported dieting was not associated with energy intake among men with higher educational levels.

DISCUSSION

Associations between self-reports of dieting and reported energy intake vary according to the phrasing of specific questions about dieting, gender, education, and weight status. These factors should be taken into account in the design of instruments for measuring these behaviors and in the interpretation of results, especially across studies using different methodologies.