Why is premorbid BMI consistently elevated in clinical samples, but not in risk factor samples, of individuals with eating disorders?

Physiological, body composition, and body mass measures show that a developmental measure of weight suppression is more valid than the traditional measure

OBJECTIVE

The traditional measure of weight suppression (TWS; the difference between an individual's highest past weight at adult height and current weight), has been associated with many psychological, behavioral and biological variables in those with eating disorders. A new measure of weight suppression, called developmental weight suppression (DWS), corrects two major problems in the original measure. Initial research indicates that DWS represents a superior operationalization of the construct weight suppression was originally designed to measure (Lowe [1993, Psychol Bull, 114: 100]). This study is the first to examine the relation between both WS measures and weight history, body composition and a variety of metabolic hormones.

METHODS

Data were collected in 91 women with bulimia nervosa (BN) or BN-spectrum disorders.

RESULTS

Both weight suppression indices were related to multiple hormones. However, multiple regression analyses showed that the independent effects of DWS differed from the independent effects of TWS in that only DWS was negatively related to: (1) current z-BMI, (2) body fat percentage, and (3) insulin, leptin, T3 free, and TSH. This differential pattern also occurred when results were corrected for multiple comparisons.

DISCUSSION

Findings provide stronger biological support for the construct validity of DWS than TWS and suggest that: (1) from the perspective of individuals with BN, high DWS embodies success at food restriction and weight loss, (2) elevated DWS may trap individuals with BN in a powerful biobehavioral bind, and (3) DWS is the preferred measure of weight suppression in future research on eating disorders.

PUBLIC SIGNIFICANCE

Most individuals with bulimia nervosa lose substantial weight in the process of developing their disorder. Such weight suppression is related to many characteristics of those with the eating disorder bulimia nervosa. This study shows why a new measure of weight suppression, based on an individual's growth during development, is more biologically valid than the traditional measure of weight suppression.

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.

Childhood body mass index and the subsequent risk of anorexia nervosa and bulimia nervosa among women: A large Danish population-based study

OBJECTIVE

Evidence linking childhood body mass index (BMI) with subsequent eating disorders is equivocal. Potential explanations include different study populations and size, and that anorexia nervosa (AN) and bulimia nervosa (BN) should be studied separately. We examined whether birthweight and childhood BMI were associated with subsequent risk of AN and BN in girls.

METHOD

We included 68,793 girls from the Copenhagen School Health Records Register born between 1960 and 1996 with information on birthweight and measured weights and heights obtained from school health examinations at ages 6-15 years. Diagnoses of AN and BN were retrieved from Danish nationwide patient registers. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

We identified 355 cases of AN (median age: 19.0) and 273 cases of BN (median age: 21.8). Higher childhood BMI was linearly associated with decreasing risk of AN and increasing risk of BN at all childhood ages. At age 6, the HR for AN was 0.85 (95% CI: 0.74-0.97) per BMI z-score and the HR for BN was 1.78 (95% CI: 1.50-2.11) per BMI z-score. Birthweight >3.75 kg was associated with increased risk of BN compared to a birthweight of 3.26-3.75 kg.

CONCLUSION

Higher BMI in girls at ages 6-15 years was associated with decreasing risk of AN and increasing risk of BN. Premorbid BMI could be relevant for the etiology of AN and BN, and in identifying high risk individuals.

PUBLIC SIGNIFICANCE

Eating disorders are associated with elevated mortality, especially AN. Using a cohort of Copenhagen school children, we linked information on BMI at ages 6-15 years for 68,793 girls with nationwide patient registers. Low childhood BMI was associated with increased risk of AN, whereas high childhood BMI was associated with increased risk of BN. These findings may assist clinicians in identifying individuals at high-risk of these diseases.

Is work-family conflict a pathway between job strain components and binge eating? A cross-sectional analysis from the ELSA-Brasil study

BACKGROUND

Job strain has been reported as a trigger for binge eating, yet the underlying mechanisms have been unclear. The aim of this study was to evaluate whether work-family conflict is a pathway in the association between job strain and binge eating, considering the possible effect-modifying influence of body mass index (BMI).

METHODS

This cross-sectional analysis included 12,084 active civil servants from the multicenter Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Job strain was assessed using the Demand-Control-Support Questionnaire. Work-family conflict was considered as a latent variable comprising three items. Binge eating was defined as eating a large amount of food in less than 2 h at least twice a week in the last six months with a sense of lack of control over what and how much was eaten. Structural equation modelling was used to test the role of work-family conflict in the association between job strain and binge eating, stratifying for BMI.

RESULTS

For individuals of normal weight, positive associations were found between skill discretion and binge eating (standardized coefficient [SC] = 0.209, 95%CI = 0.022-0.396), and between psychological job demands and work-family conflict (SC = 0.571, 95%CI = 0.520-0.622), but no statistically significant indirect effect was found. In overweight individuals, psychological job demands, skill discretion, and work-family conflict were positively associated with binge eating (SC = 0.099, 95%CI = 0.005-0.193; SC = 0.175, 95%CI = 0.062-0.288; and SC = 0.141, 95%CI = 0.077-0.206, respectively). Also, work-family conflict was observed to be a pathway on the associations of psychological job demands and decision authority with binge eating (SC = 0.084, 95%CI = 0.045-0.122; and SC =  - 0.008, 95%CI =  - 0.015- - 0.001, respectively).

CONCLUSIONS

Work-family conflict partly explains effects of high levels of psychological job demands and low levels of decision authority on binge eating among overweight individuals. Moreover, skill discretion is positively associated with binge eating, regardless of BMI category.

The food restriction wars: Proposed resolution of a primary battle

Research regarding the definition and consequences of dieting has generated controversy for years. This controversy has spilled over into the public domain, especially as eating disorders and obesity have become more prevalent. One of the earliest and longest-lasting controversies involves the restrained eating framework, which was originally developed by Herman and Polivy and also strongly influenced the development of the cognitive-behavioral model of bulimia nervosa. An alternative framework for understanding the role of dieting in nonclinical and clinical groups, called the Three-Factor Model of Dieting, took a sharply different approach to defining, and understanding the impact of, dieting. This paper provides a brief historical review of the development of these divergent perspectives and updates the Three Factor Model's critical distinction between restraining eating to prevent over-consumption and dieting to lose weight. We suggest that three historical trends impacted the development of Restraint Theory in ways that unfairly impugned dieting for weight control: the emergence of the new eating disorders of bulimia nervosa and binge eating disorder, a population-based increase in loss of control eating and a population-based increase in obesity. This update is aimed in part at encouraging new research to reconcile ongoing, unresolved issues between Herman and Polivy's restrained eating model and the Three-Factor model of Dieting model. Such research might also contribute to the public's understanding of the pros and cons of dieting and to new approaches to treating eating disorders and obesity.