Does dieting lead to weight gain? A four-year longitudinal study of middle school girls

A majority of the published longitudinal research on children has reported that dieting is related to weight gain at a later point in time. The purpose of this study was to look at weight control behaviors and patterns of weight gain and loss, specifically whether dieting is related to weight gain.

Baseline data were collected from 1358 female students in grades 6 to 9 from schools in Hayward, CA, and Tucson, AZ. Data were obtained annually over a 4-year period. Paper-and-pencil questionnaires and height and weight were obtained during the students' regular classroom periods. Dieting was measured both with the single item, "In the past year, how often have you been on a diet to lose weight?" scored from "never" to "always," and with a Dieting Behavior Scale including five items on weight control behaviors. Changes in BMI z-scores were analyzed.

On average, girls who reported "never" dieting were most likely to have an increased BMI z-score at the next measurement, and those who reported "always" dieting were most likely to have a decreased BMI z-score. The same pattern was true for the Dieting Behavior Scale.

Our finding that dieting and weight gain were not related, independently of initial BMI, does not mean that dieting to lose weight is appropriate, especially among young girls. Additional research is needed both to examine this relationship and to determine exactly what behaviors children are engaging in when they report that they are dieting.