Background. This study compared the effectiveness of cognitive therapy (CT), nutritional therapy (NT), the combination of cognitive and nutritional therapy (CNT), against a control condition of support group (SG) in the treatment of bulimia nervosa.

Methods. One hundred female out-patients who fulfilled DSM-III-R criteria for bulimia nervosa were randomized to the four treatment groups. NT and CT were designed to cover different areas with minimal overlap, and CNT provided all of the features of both of these treatments. The control condition was conducted in a group self-help format. Each of the treatments lasted 14 weeks.

Results. All three active treatments as well as SG produced significant decreases in binge/vomit episodes. Intent-to-treat analysis found CNT and CT to be significantly more effective than SG in retaining subjects in treatment and completion of study, as well as in producing greater improvements in dysfunctional attitudes and self-control. CNT was superior to SG in achieving abstinence from bulimic behaviour. NT was superior to SG only in increase of self-control. Logistic regression found that the cognitive component, whether given alone or in conjunction with NT, and higher pre-treatment self-control scores were significant predictors for both completion of study and abstinence.

Conclusion. CT (either alone, or in combination with nutritional therapy) remains the treatment of choice for bulimia nervosa. A treatment escalation approach should be tested for the treatment of bulimia with the more intensive and less widely available CT (with or without nutritional counselling) offered after patients have failed the less intensive and more widely available support group treatment.