Objective. To assess whether dieting to control weight was associated with weight change among children and adolescents.
Methods. A prospective study was conducted of 8203 girls and 6769 boys who were 9 to 14 years of age in 1996, were in an ongoing cohort study, and completed at least 2 annual questionnaires between 1996 and 1999. Dieting to control weight, binge eating, and dietary intake were assessed annually from 1996 through 1998 with instruments designed specifically for children and adolescents. The outcome measure was age- and sex-specific z score of body mass index (BMI).
Results. In 1996, 25.0% of the girls and 13.8% of the boys were infrequent dieters and 4.5% of the girls and 2.2% of the boys were frequent dieters. Among the girls, the percentage of dieters increased over the following 2 years. Binge eating was more common among the girls, but in both sexes, it was associated with dieting to control weight (girls: infrequent dieters, odds ratio [OR]: 5.10; frequent dieters, OR: 12.4; boys: infrequent dieters, OR: 3.49; frequent dieters, OR: 7.30). During 3 years of follow-up, dieters gained more weight than nondieters. Among the girls, frequency of dieting was positively associated with increases in age- and sex-specific z scores of BMI (β = 0.05 and β = 0.04 for frequent and infrequent dieters vs nondieters). Among the boys, both frequent and infrequent dieters gained 0.07 z scores of BMI more than nondieters. In addition, boys who engaged in binge eating gained significantly more weight than nondieters.
Conclusions. Although medically supervised weight control may be beneficial for overweight youths, our data suggest that for many adolescents, dieting to control weight is not only ineffective, it may actually promote weight gain.
Comments
The authors reply to "dieting causes weight gain?"
We do not agree with Dr. DiTraglia's suggestion on how to interpret the findings from our study. There is limited support for set point theory among adult humans and we are unaware of any investigations of the validity of the theory for children and adolescents, among whom weight and height should be changing.
Asking children and adolescents "What is the most you have ever weighed" instead of annually collecting information on weight would not be very useful in this age range. For the majority of participants, each year they would weigh more than the last because they are still growing. Our study is a prospective cohort study. In the analysis we assessed whether dieting at the start of a one-year interval predicted changes in weight over the following year.
There are many studies that have found a cross-sectional association between body weight and bulimic behaviors, but that does not mean that "bulimia is an important manifestation of the power of the set point." One cannot draw inference about the temporal order of an association or infer causality from cross sectional results. Moreover, we fail to see link between the association of bulimia to set point theory and the observation that 90% of women in a college dorm reported that they weighed less than the most they had ever weighed.
We concur that dieting rarely works. As we mentioned earlier, dieters were more likely than non-dieters to binge eat. We believe repeated cycles of overeating, between the restrictive diets, rather than the diets per se, may be responsible for weight gain.
dieting causes weight gain?
The study of Field et al. suggests that dieting may promote weight gain. This seems anomalous.
Set point pressure may be a way to explain this finding. It is well known that most people stay the way they are - fat or otherwise - over long periods. The set point theory describes this observation.
If frequent dieters were at some point below their set points at enrollment they would be more likely to regress.
A simple way to check this is to ask, "What is the most you have ever weighed." Dieters know this number. Assuming that most people, especially obese people,are not trying to gain weight on purpose, the most they have ever weighed would be close to their set point.
Bulimia is an important manifestation of the power of the set point. In 1989 we surveyed young women in a dorm at Ohio State University as part of a study of bulimia. Ninety percent said that they weighed less than the most they had ever weighed.
Dieting doesn't work but it probably doesn't cause weight gain.