Predictive significance of changes in dietary restraint in obese patients with binge eating disorder during treatment.

Binge Eating Disorder (BED) is characterized by recurrent binge eating in the absence of inappropriate weight control methods. BED has a prevalence of roughly 3.5% in adults and is strongly associated with obesity and therefore with increased morbidity associated with excess weight (1). BED is also associated with heightened eating disorder psychopathology, psychological distress, and psychiatric problems (2). Evidence supports the validity and the distinctiveness of BED from other eating disorder groups and from obese patients who do not binge eat (2,3). Effective treatments for BED need to address the disordered eating, associated psychopathology, and excess weight. A number of psychological (4) and pharmacological (5) interventions have efficacy for BED. Critical meta-analytic (6) and qualitative reviews (4) have concluded that a specific form of cognitive-behavioral therapy (CBT) has the strongest empirical support. CBT generally produces binge abstinence in roughly 50% of BED patients, but – like most findings for alternative psychological and behavioral treatments – does not result in meaningful weight loss for most patients (4). Similarly, a meta-analysis of pharmacotherapy treatments concluded that certain medications (anti-obesity and anti-epileptic agents) have a clinically significant advantage over placebo for producing short-term binge abstinence and weight loss, although the weight losses are modest (5). Some studies have found that adding certain medications (such as topiramate or orlistat) to CBT may enhance weight losses (7,8); however, most studies of combined psychological and pharmacological approaches have not found additive effects (5). Finding ways to improve binge eating and weight loss outcomes represents a major research priority. A clearer understanding of the processes involved in treatments with some efficacy is needed in order to further refine these treatments (4). In the case of BED, it seems especially important to elucidate the nature and role of restraint. The excess weight in patients with BED is likely attributable to a combination of the binge eating and a general lack of dietary “restraint.” In contrast, extreme dietary “restraint” is a salient characteristic of other eating disorders and typically results in normal or low weight (3). CBT for BED essentially follows, with a few adaptations, the CBT approaches developed initially for bulimia nervosa (9), which attempts to reduce extreme dietary restraint – a proposed maintaining factor for binge eating. This approach is somewhat at odds with traditional weight loss treatments for obesity that attempt to increase dietary restraint in order to produce weight loss (10). The role of “restraint” in these different patient groups remains poorly understood due, in part, to measurement and conceptual issues regarding the different aspects of “restraint” and its various measures (11,12,13). The nature of changes in different aspects of dietary restraint during treatment has received little empirical attention although emerging research has been informative. Safer and colleagues (11), in a study of BN patients receiving CBT, found that the restraint scale of the Eating Disorder Examination interview (EDE; 14) significantly declined during treatment and was associated with decreased binge frequency whereas the cognitive restraint scale of the Three Factor Eating Questionnaire (TFEQ; 15) was not associated with binge reduction. Downe, Goldfein, and Devlin (16), in a study of BED patients receiving BWL augmented with either CBT, fluoxetine, or placebo, examined the nature of changes in the TFEQ (also referred to as the Eating Inventory) cognitive restraint scale as well as in changes in its two subscales (flexible restraint and rigid restraint). Both flexible and rigid restraint scores increased during treatment but flexible restraint was more closely associated with post-treatment binge abstinence and weight loss (16). The different findings across these studies likely reflect, in part, several factors. First, BN and BED differ markedly in restraint; BN tends to be characterized by high levels of most forms of dietary restraint including extreme restrictive behaviors whereas BED tends to be associated with low levels of both healthy and unhealthy dietary restraint. Second, Safer et al (11) considered the TFEQ cognitive restraint scale but, unlike Downe et al (16), failed to examine the flexible and rigid subscales whereas Downe et al (16) did not evaluate changes in the EDE restraint scale. Third, Safer et al (11) examined changes with CBT whereas Downe et al (16) examined changes with BWL (augmented with various treatments). Safer and colleagues (11) highlighted the need for continued research to refine further our understanding of dietary restraint in different patient groups and noted that, ideally, research should compare all of these restraint measures throughout a treatment study within specific patient groups. In the present study, we examined changes in different aspects of dietary restraint in obese patients with BED receiving cognitive-behavioral-therapy guided-self-help (CBTgsh) combined with either orlistat or placebo and whether changes in these different restraint variables predicted outcomes at post-treatment and at 3-month follow-up. We hypothesized that decreased unhealthy forms of restraint as measured by the restraint scale of the Eating Disorder Examination Questionnaire (EDE-Q; 17) and the TFEQ rigid restraint subscale would predict binge abstinence and that increases in all three restraint scales (EDE-Q restraint, TFEQ rigid restraint, TFEQ flexible restraint) would predict weight loss.