Eating disorders (EDs) exist on a continuum ranging from innocuous but persisting dieting, through subthreshold states of uncertain significance, to full-blown cases of anorexia nervosa (AN) and bulimia nervosa (BN). Subthreshold EDs resemble AN or BN, but do not meet all their diagnostic criteria. The terms “partial syndromes” and “atypical EDs” are also used to identify these conditions.Objectives. To verify whether atypical syndromes are less severe forms of EDs or represent starting phases of EDs, we designed a two-step prospective study assessing the natural outcome of those syndromes over a 4-year time period.

In the first step, we screened 495 female students attending the first year of their high school by means of ad hoc rating questionnaires. Those students identified to being at risk for an ED underwent a psychiatric diagnostic interview. In the second step, 4 years later, we reassessed 140 of those schoolgirls who had participated in the first step.

In the first step, we identified 1 subject with full-blown BN, 1 with partial-syndrome BN, 2 with subclinical BN and 8 with subclinical AN. At the reassessment 4 years later, none of the girls had received any form of help. The full-blown BN case, the partial-syndrome BN case and 1 of the subclinical AN cases persisted unchanged; 1 of the subclinical BN cases shifted to subclinical AN; the remaining subclinical cases remitted spontaneously.

Present findings provide the evidence that subclinical AN and subclinical BN represent unstable states that can spontaneously remit over time.