Relation of Dieting and Voluntary Weight Loss to Psychological Functioning and Binge Eating

Dieting and Weight Loss in Obese Persons Weight loss treatments combining dietary control with increased exercise and other lifestyle changes are effective in producing weight loss in persons with mild (20% to 40% overweight) to moderate (40% to 100% overweight) obesity [1]. This weight loss is successfully maintained in the short term (6 to 12 months) in roughly two thirds of patients [2-4]. Both positive and negative psychological sequelae of these weight loss treatments have been reported. The most extensively studied psychological consequence of diet-induced weight loss has been depression. Although studies completed before 1980 found that weight loss was associated with increased depression [5], subsequent studies have shown decreases in depression of 50% or more in the short term [4, 6]. In a comprehensive review of the literature, Smoller and colleagues [7] argued that changes in depression occurring after weight loss have been primarily a function of the method used to assess psychological effects. Reported adverse reactions may have been the result of interpretive bias in that they were ascertained through retrospective and subjective assessment. Reported beneficial effects of weight loss have been shown by more objective outcome measures. Although dietary and behavioral treatments have produced reliable and significant decreases in depression and anxiety from pre- to post-treatment stages, transient increases in negative affect have been noted during the course of treatment [7]. In one study, 54% of patients reported an increase of 25% or more in depressive symptoms at some point during the course of treatment [8]; however, transient emotional changes are common in psychological therapy for most clinical disorders. Furthermore, the absence of a nondieting control group in these studies precludes the attribution of these transient mood fluctuations to dieting itself. Behavioral weight control treatments also result in other beneficial short-term psychological effects. Body-image dissatisfaction is decreased and body-size estimation is reduced [9, 10]. Enhanced self-esteem, improved interpersonal functioning, and increased marital satisfaction have also been reported. Surgical treatments of morbid obesity have produced consistently beneficial effects on self-esteem, mood, body image, interpersonal functioning, and sexual relations in most patients [11, 12]. Dieting and Weight Loss in Normal-Weight Persons Persons of normal weight show reactions to dieting that differ markedly from those seen in overweight persons. The negative effects of extreme dieting were shown by Keys and colleagues' [13] study of young men on a semistarvation diet that resulted in the loss of roughly 25% of their body weight. Extreme negative emotional reactions were common. More conventional, self-initiated dieting is also associated with adverse psychological effects in young women of normal weight. Cross-sectional studies of adolescent girls have indicated that, independent of the effect of body weight itself, dietary restraint is correlated with feelings of failure, lowered self-esteem, and depressive symptoms [14-16]. Dieting has also been shown to predict stress [17]; however, stress is not a predictor of dieting. The Link of Dieting to Eating Disorders Bulimia nervosa is an eating disorder characterized by the uncontrolled consumption of large amounts of food (binge eating), compensatory behaviors aimed at avoiding weight gain (for example, purging), and abnormal attitudes toward body weight and shape. Anorexia nervosa is marked by the same attitudinal disturbance and a body weight of at least 15% less than expected. Roughly one half of patients with anorexia nervosa also binge or purge [18]. A striking feature of these eating disorders is that they are largely confined to women. The gender-related prevalence of eating disorders seems to be linked directly to the fact that women, driven by psychosocial pressure to achieve the culturally determined ideal of physical beauty, diet more frequently than do men. Anorexia Nervosa and Bulimia Nervosa Several lines of evidence suggest that dieting is closely linked to anorexia nervosa and bulimia nervosa. Clinical descriptions consistently indicate that patients with bulimia nervosa almost always report that their binge eating began when they were on a diet [19, 20]. Dieting is a prominent, albeit often neglected, feature of bulimia nervosa [21] and is one of the most difficult to change. In addition, renewed dietary restriction after successful treatment of bulimia nervosa is a common cause of relapse. Eating disorders are most common in the specific groups that are most involved in dieting and weight losspredominantly white, middle- to upper-class women. An overall correlation appears to exist between cultural pressure to be thin and prevalence of eating disorders both across and within different ethnic groups [22]. Eating disorders occur more frequently among persons involved in occupations [23] and sports [24] that require low body weight. Two prospective studies have linked dieting to the development of eating disorders. Patton and colleagues [25] studied a representative sample of 15-year-old school girls in London. Compared with nondieters, dieters were significantly at risk for developing an eating disorder within 1 year. Only a small portion of the girls who were dieting at the beginning of the study (21%) subsequently were diagnosed as having an eating disorder, but dieters were eight times more likely than nondieters to develop an eating disorder. The second prospective analysis comes from Kendler and associates [26], who studied more than 1000 female twins located through the Virginia Twin Registry. Self-reported weight fluctuation (maximum to minimum weight) and current dieting status predicted the diagnosis of bulimia nervosa during a subsequent interview conducted 1 to 3 years later. Additional evidence comes from laboratory studies of what Polivy and Herman [27] have called restrained eaters. Restrained eaters typically consume less food than their unrestrained counterparts [28]. Although the findings from laboratory studies of restrained eating are complex, attention has been focused on the finding that restrained eaters differ from unrestrained eaters in the amount of food they eat after having consumed an actual or perceived high-calorie preload [29]. In these studies, unrestrained eaters typically regulate their eating so that they eat less after a preload than do those who do not receive a preload. Restrained eaters have been shown to regulate their intake in the absence of a preload but to eat significantly more in a taste test conducted after consumption of a preload. This pattern of disinhibited eating has been called counter-regulation and has been put forward as an experimental analog of binge eating. Restrained eaters have shown similar disinhibition of consumption under the influence of a negative emotional state [30], which is also characteristic of clinical binge eating. Binge Eating in the Obese Approximately 30% of obese patients seeking weight control treatment meet the diagnostic criteria of what Spitzer and colleagues [31] have described as binge-eating disorder. Persons with this disorder engage in recurrent binge eating but do not meet the diagnostic criteria for bulimia nervosa because no compensatory behavior (for example, purging) or comparable attitudinal disturbance exists. The available evidence on the association between dieting and binge eating in obese patients is less clear, however, than in anorexia nervosa and bulimia nervosa. Comparisons of obese binge eaters and non-binge eaters have not shown greater dietary restraint in the former, although differences in assessment methods and patient samples make comparisons among studies difficult. Two comparisons of obese patients with and without binge eating showed no difference on the restraint scale of Stunkard and Messick's [32] Three Factor Eating Questionnaire [33, 34]. Wilson and coworkers [35] found that only a minority of obese binge eaters reported being on a strict diet at the time that binge eating began. Furthermore, binge eaters did not differ from nonbingers on several diet-related activities, such as restriction of food to influence body weight, avoidance of eating, avoidance of specific foods, and adherence to definite rules about food intake. Using a semistructured clinical interview (the Eating Disorder Examination) [36], Marcus and colleagues [37] found that obese binge eaters practiced less dietary restraint than did patients of normal weight who had bulimia nervosa and did not differ from normal-weight, nonbulimic restrained eaters on dietary restraint. Similarly, Rossiter and colleagues [38] found that overweight patients with binge-eating showed less dietary restraint than did patients with bulimia nervosa, but more restraint than normal, on self-monitored caloric intake during binge-free days and on a questionnaire measuring dietary restraint. These investigators suggested that it is advisable for such overweight persons to restrict their food intake to lose weight. The alternative view is that continued dietary restriction serves only to perpetuate binge eating and should be discouraged [39, 40]. Concern has been expressed that, because of their restriction and rigidity, very-low-calorie diets (VLCDs) might precipitate binge eating. In a study of obese patients with type II diabetes, Wing [6] compared the rates of dietary lapses during behavioral treatment combined with either a VLCD (400 kcal/d) or a balanced diet (1000 to 1500 kcal/d). The two dietary programs did not differ on either objective (intake of food 20% or more above daily calorie goal) or subjective (patients' perceptions that they had transgressed calorie limits) lapses. Telch and Agras [41] assessed the frequency of binge-eating episodes during a combined VLCD and behavioral weight-loss program. Afte