The two aims of the present study were to identify the characteristics of the dieters most at risk of subsequently developing an eating disorder and to evaluate the feasibility of using a brief questionnaire to identify such dieters in advance. This necessitated recruiting a large community-based group of young women, identifying a subgroup who were currently dieting, and then following up on them at repeated intervals to see who had developed an eating disorder and who had not. These steps were accomplished, and both aims were achieved. It should be noted that the dieters were identified on the basis of a high score on a measure of dietary restraint—that is, a measure of attempting
to restrict food intake—rather than a measure of actual dietary restriction. There is limited evidence that the two are separable (28
). Both dietary restraint and dietary restriction are thought likely to increase the risk of developing an eating disorder through cognitive and physiological mechanisms, respectively.
As expected, only a small proportion of the dieters developed an eating disorder, and most were cases of eating disorder not otherwise specified. This high proportion of subjects with eating disorder not otherwise specified relative to subjects with anorexia nervosa and bulimia nervosa parallels the distribution of the three diagnoses in most clinical settings (29
). Not surprisingly, the dieters who developed an eating disorder had more disturbed eating habits and attitudes at recruitment than those who did not, as reflected in their higher scores on the global subscale of the Eating Disorder Examination Questionnaire. Also unsurprising is the fact that several of the features that best discriminated future cases from future noncases were features that are seen in people with eating disorders, albeit at a more severe level. Other ominous features were less predictable: namely, eating in secret; preoccupation with food, eating, shape, or weight; fear of losing control over eating; and wanting to have a completely empty stomach.
There was substantial overlap in the items on the Eating Disorder Examination Questionnaire selected by the three different statistical methods. The efficiencies of the instruments derived from the discriminant function and the decision tree analyses were similar and the same as those from a simple case-predicting instrument derived from one of five items scoring above the optimal cut point (sensitivity=71%, specificity=72%). Both methods would involve completing a brief questionnaire that would identify about 70% of future cases.
The strengths of the present study include the size of the cohort, which resulted in a sufficiently large number of dieters being studied for 104 cases of eating disorder cases to develop; the method of recruitment, which circumvented certain of the selection biases that would have resulted had we advertised for dieters; and the 2-year follow-up, which provided sufficient time for many cases to develop. Other strengths include the use of clinical methods and thresholds to define case status and the fact that the core measure, the Eating Disorder Examination Questionnaire, has been well validated and is known to be acceptable to the relevant population. The relatively high rates of response are also of note.
A limitation of the study is its reliance on a measure of eating habits and attitudes to predict future case status instead of also testing the performance of other variables. We decided to focus on eating habits and attitudes for three largely pragmatic reasons. First, given current knowledge about risk factors for eating disorders (5
), we thought that eating habits and attitudes were likely to be better predictors of developing an eating disorder than other variables. Second, we thought that young women who are dieting would be more willing to answer questions about their eating habits than questions about other aspects of their lives. Third, we were concerned about overburdening our participants with questions, given that they had little reason to participate. The addition of other variables might have enhanced our ability to predict future case status. Another limitation is the age and gender of the group because it did not include participants under 16 years old or men. Although an attempt has already been made to develop an instrument for use with younger teenagers (30
), the relative rarity of eating disorders among men precludes them from a study of this type. A third limitation is that the participants were followed up for just 2 years, so some later-onset cases will have been missed. Fourth, the fact that those who did not comply with follow-up had higher scores on the Eating Disorder Examination than those who did may have influenced the findings. Finally, because all of our analyses were necessarily exploratory, the desirability of replication must be stressed, although in this instance, opportunities may be limited given the scale required of the research project.
In conclusion, this study has shown that young female dieters who will develop an eating disorder within the next 2 years have distinctive features and that it is potentially feasible to identify them in advance. The case-predicting questionnaire required is brief and easy to complete and score, and its content is acceptable to young women. It could therefore be incorporated into routine health assessments. Women scoring positively could be flagged, with this information made available to inform subsequent consultations. In addition, these women could be the focus of preventive interventions (31
). The findings may also be of relevance to young women considering embarking on weight-loss programs because the combination of dietary restraint and the features identified in the present study would confer a higher risk of developing an eating disorder. It could be argued that such women should be informed of this risk and perhaps advised against embarking on such programs. If they chose to go ahead, it would seem wise for them to do so cautiously and perhaps with some external monitoring.