Decrease in resting metabolic rate during abstinence from bulimic behavior

Weight History Correlates of Resting Energy Expenditure in Women With Bulimia Nervosa

OBJECTIVE

Among those with bulimia nervosa, weight suppression has been associated with illness severity and treatment prognosis. Although significant weight loss is known to reduce metabolic rate, the relation between weight suppression and resting energy expenditure (REE) in bulimia nervosa has not been examined. This study tested the hypothesis of an inverse relation between weight suppression and REE in a sample of women with bulimia nervosa (N = 84).

METHODS

In primary analyses, linear regressions were conducted between weight suppression and REE, corrected for fat-free mass. In follow-up, exploratory analyses, stepwise linear regressions were conducted to explore the main and interaction effects of weight history and weight suppression on REE.

RESULTS

Neither traditional (TWS) nor developmental weight suppression (DWS) correlated with REE. Results from exploratory analyses, however, revealed a medium-to-large inverse relation between several weight history variables and REE (highest past weight, sr2 = 0.05; lowest postmorbid weight, sr2 = 0.07; current weight, sr2 = 0.05). Additionally, DWS interacted with current (sr2 = 0.08) and highest premorbid (sr2 = 0.05) z-BMI to influence REE with a medium-to-large effect. For individuals low in current and premorbid z-BMIs, higher DWS associated with lower REE levels. However, for individuals at higher premorbid z-BMIs, higher DWS unexpectedly associated with greater REE levels.

DISCUSSION

In this sample of women with bulimia nervosa, reduced REE associated with higher weights across all timepoints. If the interaction effect between DWS and z-BMI history persists in future studies, this may indicate unique challenges faced by individuals low in z-BMI and high in DWS related to weight gain and normalization of eating.

A Meta-analysis on Resting State High-frequency Heart Rate Variability in Bulimia Nervosa

OBJECTIVE

Autonomic nervous system function is altered in eating disorders. We aimed to quantify differences in resting state vagal activity, indexed by high-frequency heart rate variability comparing patients with bulimia nervosa (BN) and healthy controls.

METHODS

A systematic search of the literature to identify studies eligible for inclusion and meta-analytical methods were applied. Meta-regression was used to identify potential covariates.

RESULTS

Eight studies reporting measures of resting high-frequency heart rate variability in individuals with BN (n = 137) and controls (n = 190) were included. Random-effects meta-analysis revealed a sizeable main effect (Z = 2.22, p = .03; Hedge's g = 0.52, 95% CI [0.06;0.98]) indicating higher resting state vagal activity in individuals with BN. Meta-regression showed that body mass index and medication intake are significant covariates.

DISCUSSION

Findings suggest higher vagal activity in BN at rest, particularly in unmedicated samples with lower body mass index. Potential mechanisms underlying these findings and implications for routine clinical care are discussed. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Binge Eating Disorder: Current Knowledge and Future Directions

Binge eating disorder (BED) is a newly characterized eating disorder that encompasses individuals who have severe distress and dysfunction due to binge eating, but who do not regularly engage in inappropriate compensatory behaviors. While relatively uncommon in the general community, BED becomes more prevalent with increasing severity of obesity. BED is associated with early onset of obesity, frequent weight cycling, body shape disparagement, and psychiatric disorders. These associations occur independent of the degree of obesity. Although many individuals with BED have good short-term weight loss regardless of treatment modality, as a group they may be prone to greater attrition during weight-loss treatment and more rapid regain of lost weight. Current treatments geared toward binge eating behaviors include antidepressant medications, cognitive behavioral psychotherapy, and interpersonal psychotherapy; however, these treatments have little efficacy in promoting weight loss, and only modest success in long-term reduction of binge eating. As a significant proportion of obese individuals entering weight-loss treatment and research programs are likely to meet criteria for BED, those conducting clinical research should be aware of this distinct subgroup and determine the contribution of BED to outcome measures.

Recovery of low plasma BDNF over the course of treatment among patients with bulimia nervosa

Recent studies have suggested that brain-derived neurotrophic factor (BDNF) is associated with energy balance, eating behaviors, and psychological states such as depression. Although decreased BDNF levels in patients with bulimia nervosa (BN) have been reported, the mechanism is still unclear. Few studies have investigated longitudinal changes of BDNF in BN patients. We investigated changes in the levels of plasma BDNF before and after inpatient treatment. Subjects were 16 female patients with BN and 10 control females. The levels of plasma BDNF were measured. In seven patients who completed a 4-week inpatient treatment program based on cognitive behavior therapy, levels of plasma BDNF were measured twice, before and after inpatient treatment. Plasma BDNF levels were significantly lower in BN subjects than in controls. BDNF levels were significantly higher following inpatient treatment. Increased plasma BDNF after inpatient treatment suggests that lower plasma BDNF levels in BN patients are associated with abnormal eating behaviors, especially binge eating.

Thyroid indices and treatment outcome in bulimia nervosa

OBJECTIVE

This study examined the thyroxine (T4) and free T4 (FT4) status of women with bulimia nervosa and its value as a predictor of outcome.

METHOD

A total of 135 women with bulimia nervosa underwent 12-weeks cognitive behavioral therapy treatment. Prior to and at 3-year follow-up patients completed psychiatric assessments and serumT4 and FT4 were measured.

RESULTS

At 3-year follow-up, 71% had no eating disorder and 29% met criteria for any eating disorder diagnosis. Mean T4 and FT4 concentrations were within normal ranges. Pre-treatment T4 and FT4 concentrations were inversely associated with food restriction and purging frequency, respectively. Compared with women with no eating disorder, those with any eating disorder at follow-up had lower pretreatment T4 concentrations. When pre-treatment food restriction, oral contraceptive use and binge frequency where controlled for, low T4 concentration was the only predictor of eating disorder diagnosis at follow-up.

CONCLUSION

Low T4 concentrations at pretreatment may be a predictor of poor outcome in bulimia nervosa.

Research on energy expenditure in individuals with eating disorders: a review

OBJECTIVE

This study reviews the published research on energy expenditure in individuals with anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).

METHOD

Individual studies are reviewed and their results summarized.

RESULTS

The most consistent finding is a reduction in resting energy expenditure (REE) in patients with AN, which increases with increased energy intake and body weight. Data regarding BN are inconsistent. Three available studies in subjects with BED have not found evidence of changes in energy expenditure corrected for lean body mass compared with obese non-binge eaters.

DISCUSSION

The ability to measure REE reliably and cost-effectively may aid in the refeeding of patients with AN in whom REE is reduced. Changes in individuals with BN and BED have yet to be consistently identified.

Research on energy expenditure in individuals with eating disorders: a review

OBJECTIVE

This study reviews the published research on energy expenditure in individuals with anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).

METHOD

Individual studies are reviewed and their results summarized.

RESULTS

The most consistent finding is evidence of reduction in resting energy expenditure (REE) in patients with AN, which increases with increased energy intake and body weight. Data regarding BN are inconsistent. Three available studies in subjects with BED have not found evidence of changes in energy expenditure corrected for lean body mass compared with obese non-binge eaters.

DISCUSSION

The ability to reliably and cost-effectively measure REE may aid in the refeeding of patients with AN where REE is reduced. Changes in BN and BED subjects have yet to be identified consistently.

Total energy expenditure as measured by doubly-labeled water in outpatients with bulimia nervosa

OBJECTIVE

This study measured total energy expenditure (TEE) in symptomatic outpatient women with bulimia nervosa and normal controls. The study aimed to test the conceptual model of bulimia nervosa as an illness characterized by a physiological state of starvation, despite normal weight.

METHOD

Total fat and fat-free mass were measured using hydrodensitometry and total energy expenditure was assessed via the doubly-labeled water method, in nine normal weight outpatient females with DSM-III-R bulimia nervosa and ten healthy female controls.

RESULTS

Patients and controls were similar in age, body mass index, weight, lean body mass, and levels of exercise and general activity. Patients had an average baseline binge frequency of 14.7 episodes per week and purge frequency of 16.8 times per week, and had been ill for an average of 11.9 years. Group mean TEE did not differ between patients and controls (patients 2380 +/- 482 kcal/day, controls 2368 +/- 515 kcal day). Observed TEE in the bulimic subjects did not differ significantly from TEE predicted on the basis of data from the controls.

DISCUSSION

This finding of normal TEE in symptomatic outpatients with bulimia nervosa is consistent with a previous study that found no difference in TEE in a sample of symptomatic inpatients with bulimia nervosa. These data suggest that the energy conserving metabolic adaptations characteristic of semi-starvation do not occur in patients with bulimia nervosa.

Body weight in bulimia nervosa

OBJECTIVES

The objectives of this study were to determine: 1) factors associated with body mass index (BMI) in women with bulimia nervosa prior to treatment; 2) changes in BMI during cognitive behavioral therapy (CBT) for bulimia nervosa; and 3) predictors of weight change during CBT treatment.

METHODS

Participants were 94 women with DSM-III-R bulimia nervosa enrolled in a randomized clinical trial of CBT. Eating disorder symptomatology, past and current psychopathology, and BMI were measured prior to treatment and after twelve weeks of treatment.

RESULTS

A significantly lower BMI prior to treatment was independently associated with a history of anorexia nervosa, substance use, cigarette smoking, and a high frequency of vomiting. Reductions in binge eating, purging, and food restriction after treatment did not result in significant changes in BMI. Increasing age, higher maximum lifetime body weight, and a high frequency of binge eating at baseline predicted weight gain during treatment. Weight loss during treatment was predicted by a high frequency of vomiting, and elevated levels of body dissatisfaction prior to treatment.

DISCUSSION

Patients hesitant to engage in treatment for fear of weight gain upon cessation of their bulimic behaviors should be reassured that CBT is not usually accompanied by substantial weight gain. Identification of women at risk of significant weight gain or loss during CBT may enable therapists to focus on its aspects that help to prevent excessive body weight changes.

Biological correlates of binge eating

Eating disorders are associated with numerous biological perturbations; however, sorting out cause from effect is difficult. Neuroendocrine and metabolic abnormalities are seen in both anorexia nervosa and bulimia nervosa, but they have not been described in binge eating disorder, in which neither starvation nor compensatory behaviors are present. Although these findings may reflect biologic differences among subgroups of binge eaters, an alternative explanation is that many of the biological correlates of binge eating are the result of metabolic derangement secondary to starvation and/or purging. The identification of binge eating disorder provides an opportunity to study the causes and concomitants of binge eating in the absence of compensatory behaviors.

Recorded food intake of obese women with binge eating disorder before and after weight loss

Because binge eating in obese individuals has been postulated to be a reaction to dietary restriction, we examined the recorded food intake of 17 obese women with and 16 obese women without binge eating disorder (BED) during 1-week periods before and 3 months after a very low calorie diet program in order to determine the effects of dietary restriction on binge eating frequency and severity. Before weight loss, rather than reporting severe caloric restriction, women with BED reported greater average energy intake than nonbinge eaters on both a total (2707 vs. 1869 k cal/day, p < .01) and weight-adjusted (25.1 vs. 18.1 kcal/kg, p < .01) basis, with both higher intake on nonbinge days and an increased frequency of binge days. After weight loss, there was no significant difference in energy intake, on either a total or weight-adjusted basis, between subjects with and without BED. Although average daily energy intake fell for both groups after weight loss, only subjects with BED reported significantly decreased energy intake when adjusted for change in body weight. This resulted from decreased intake on nonbinge days and a decreased frequency of binge days. Before weight loss, subjects with BED reported an average energy intake equivalent to 94% of their predicted energy expenditure. Whereas subjects without BED reported intake only 64% of predicted (p = .002). After weight loss, there was no significant difference between subjects with and without BED in the percentage of predicted energy expenditure reported as intake (64% vs. 58%). Restraint was similar in both groups before weight loss, but those with BED reported greater hunger and disinhibition. After weight loss treatment, restraint increased significantly, whereas disinhibition and hunger remained elevated in subjects with BED. Disinhibition, rather than restraint, appears to be a major contributor to the disordered eating of these individuals. Unlike normal-weight women with bulimia nervosa, dietary restriction does not appear to worsen symptoms of binge eating in obese women with BED. Over the short term, subjects with BED may respond to a standard weight loss treatment program with improvements in binge eating behaviors.

Team treatment of eating disorders

The treatment of eating disorders requires the expertise of a multidisciplinary team. This case presents the psychologic and physiologic challenges observed in managing these patients. Attention must be directed toward the use of techniques to obtain a commitment from patients to meet a therapeutic goal. Care must be taken to avoid overaggressive feeding of patients with eating disorders to avoid the refeeding syndrome.

Thyroid function in bulimia nervosa

Bulimia nervosa is characterized by episodes of binge eating. Bulimic patients have diminished caloric requirements and reduced metabolic rate. Because thyroid function is an important modulator of metabolic rate, we sought to clarify conflicting reports concerning this parameter in bulimic patients. Thyroid indices were examined in 18 bulimics at admission and after 3 weeks of abstinence. Patients had thyroid indices in the normal range at admission but slightly diminished triiodothyronine (T3) compared with control subjects (n = 28). Significant declines in T3 and thyroxine and increases in thyrotropin were noted after 3 weeks of abstinence. At abstinence, T3 was positively correlated with caloric intake, protein, fat, and carbohydrate consumption and inversely correlated with percent ideal body weight. We hypothesize that binge-purge behavior may transiently increase thyroid indices and, consequently, metabolic rate in patients with bulimia nervosa. Furthermore, decreases in T3 following abstinence may be related to diminished caloric consumption or may reflect hypothalamic-pituitary dysregulation in these patients.