Patterns of weight-control behavior among 15 year old girls

Abstract

Objective: The objectives were to identify and predict patterns of weight-control behavior in 15 years old (yo) girls and to examine weight-control group differences in energy intake.

Method: Participants included 166 girls assessed every 2 years (ys) from age 5 to 15. Latent class analysis was used to identify patterns of weight-control behaviors. Antecedent variables (e.g., inhibitory control at 7 ys), and concurrent variables (e.g., BMI and dietary intake at 15 ys) were included as predictors. Assessments were a combination of survey, interview, and laboratory measures.

Results: Latent class analysis (LCA) identified four classes of weight-control behaviors, nondieters (26%), and three dieting groups, namely lifestyle (16%), dieters (43%), and extreme dieters (17%). Levels of restraint, weight concerns, and dieting frequency increased across groups, from nondieters to extreme dieters. Body mass index (BMI) at 5 ys and inhibitory control at 7 ys predicted weight-control group at 15 ys; for example, with every one point decrease in inhibitory control, girls were twice as likely to be extreme dieters than nondieters. Girls in the extreme dieters group were mostly classified as under-reporters and had the lowest self-reported intake, but ate significantly more in the laboratory.

Discussion: Among 15 yo girls, "dieting" includes a range of both healthy and unhealthy behaviors. Risk factors for membership in a weight-control group are present as early as 5 ys. Patterns of intake in the laboratory support the view that lower reported energy intake by extreme dieters is likely due under-reporting as an intent to decrease intake, not actual decreased intake.

Keywords: adolescents; dietary intake; dieting; weight control.

Figure 1

Probability of reporting each weight-control behavior, conditional on membership in weight control group (N=166)

Figure 2

Self-reported and weighed dietary intakes are shown by weight control group. Self-reported intake (A) based on 3 24h multiple-pass dietary recalls. Percent underreporting differed by group (61% for Non-dieters, 58% for Lifestyle, 75% for Dieters, and 96% for Extreme Dieters). Weighed intake (B) was measured at lunch and the Eating in Absence of Hunger (EAH) paradigm. 1,015 kcal were offered at the lunch, and 2,235 kcal were offered during EAH. Data are shown as means plus standard error. Means sharing the same superscript are not significantly different from each other (P<0.05).