Eating behavior in bulimia

A comparison of food-based decision-making between restricting and binge-eating/purging subtypes of anorexia nervosa

OBJECTIVE

By definition, restricting (ANR) and binge-eating/purging (ANBP) subtypes of anorexia nervosa (AN) differ in some manifestations of maladaptive eating behavior. This study aimed to determine whether the groups differ in the choices they make about what to eat, and whether there are differences in valuation related to food choice, using an experimental paradigm.

METHOD

Inpatients with ANR (n = 40) and ANBP (n = 46) participated in a Food Choice Task. During the task, participants rated 76 food images for healthiness and tastiness, and choice preferences. Groups were compared in percent selection of high-fat and low-fat foods, value ratings of foods, and engagement of self-control in food choice.

RESULTS

There were no differences between AN subtypes in healthiness or tastiness ratings, or in tendency to limit choice of high-fat foods. There was no difference between the groups in measures of self-control in food choice.

DISCUSSION

Individuals with ANR and ANBP similarly manifest reduced choices of high-fat foods, with similar tendencies to undervalue the tastiness of high-fat foods. These results suggest that while individuals with ANR and ANBP differ across a range of clinical characteristics, the decision-making process associated with the maladaptive restriction of high-fat foods characteristic of AN is shared by both subtypes.

Negative affect, dietary restriction, and food choice in bulimia nervosa

OBJECTIVE

Negative affect is a precipitant for binge eating in bulimia nervosa (BN). The purpose of the current study was to examine the effect of negative affect on food choices on a more granular level among individuals with BN using a computerized Food Choice Task.

METHOD

Individuals with BN (n = 25) and healthy controls (HC, n = 21) participated in a computerized Food Choice Task following negative and neutral affect inductions, across two study sessions. During the task participants rated high and low-fat food items for Healthiness and Tastiness. Individuals then made a series of choices between a neutral-rated food and high and low-fat foods and were then given a snack based upon these choices.

RESULTS

Overall negative affect score increased significantly for both the BN and HC groups following the negative affect induction. The group of individuals with BN, relative to the HC group, was less likely to choose high-fat foods (z = -2.763, p = 0.006), and these choices were not impacted by affect condition. Health ratings influenced food choices significantly more among individuals with BN than HC (z = 2.55, p = 0.01).

DISCUSSION

Induction of negative affect was successful, yet was not related to an increase in proportion of high-fat food choices in the group of individuals with BN. The Food Choice Task captured dietary restriction in individuals with BN and results highlight the utility of this task as a probe to examine how the values of healthiness and tastiness impact food choice in individuals with BN.

Eating disorders: Insights from imaging and behavioral approaches to treatment

Understanding factors that contribute to eating disorders, which affect 13% of females, is critical to developing effective prevention and treatment programs. In this paper, we summarize results from prospective studies that identified factors predicting onset and persistence of eating disorders and core symptom dimensions. Next, implications for intervention targets for prevention, and treatment interventions from the risk- and maintenance-factor findings are discussed. Third, given that evidence suggests eating disorders are highly heritable, implying biological risk and maintenance factors for eating disorders, we offer working hypotheses about biological factors that might contribute to eating disorders, based on extant risk factor findings, theory, and cross-sectional studies. Finally, potentially fruitful directions for future research are presented. We suggest that it would be useful for experimental therapeutics trials to evaluate the effects of reducing the risk factors on future onset of eating pathology and on reducing maintenance factors on the risk for persistence of eating pathology, and encourage researchers to utilize prospective high-risk studies so that knowledge regarding potential intervention targets for prevention and treatment interventions for eating disorders can be advanced. Using the most rigorous research designs should help improve the efficacy of prevention and treatment interventions for eating disorders.

Preference for Safe Over Risky Options in Binge Eating

Binge eating has been usually viewed as a loss of control and an impulsive behavior. But, little is known about the actual behavior of binging patients (prevalently women) in terms of basic decision-making under risk or under uncertainty. In healthy women, stressful cues bias behavior for safer options, raising the question of whether food cues that are perceived as threatening by binging patients may modulate patients’ behaviors towards safer options. A cross-sectional study was conducted with binging patients (20 bulimia nervosa (BN) and 23 anorexia nervosa binging (ANB) patients) and two control groups (22 non-binging restrictive (ANR) anorexia nervosa patients and 20 healthy participants), without any concomitant impulsive disorder. We assessed decisions under risk with a gambling task with known probabilities and decisions under uncertainty with the balloon analog risk taking task (BART) with unknown probabilities of winning, in three cued-conditions including neutral, binge food and stressful cues. In the gambling task, binging and ANR patients adopted similar safer attitudes and coherently elicited a higher aversion to losses when primed by food as compared to neutral cues. This held true for BN and ANR patients in the BART. After controlling for anxiety level, these safer attitudes in the food condition were similar to the ones under stress. In the BART, ANB patients exhibited a higher variability in their choices in the food compared to neutral condition. This higher variability was associated with higher difficulties to discard irrelevant information. All these results suggest that decision-making under risk and under uncertainty is not fundamentally altered in all these patients.

Improved planning abilities in binge eating

Objective

The role of planning in binge eating episodes is unknown. We investigated the characteristics of planning associated with food cues in binging patients. We studied planning based on backward reasoning, reasoning that determines a sequence of actions back to front from the final outcome.

Method

A cross-sectional study was conducted with 20 healthy participants, 20 bulimia nervosa (BN), 22 restrictive (ANR) and 23 binging anorexia nervosa (ANB), without any concomitant impulsive disorder. In neutral/relaxing, binge food and stressful conditions, backward reasoning was assessed with the Race game, promotion of delayed large rewards with an intertemporal discounting task, attention with the Simon task, and repeating a dominant behavior with the Go/No-go task.

Results

BN and to a lower extent ANB patients succeeded more at the Race game in food than in neutral condition. This difference discriminated binging from non-binging participants. Backward reasoning in the food condition was associated with lower approach behavior toward food in BN patients, and higher food avoidance in ANB patients. Enhanced backward reasoning in the food condition related to preferences for delayed large rewards in BN patients. In BN and ANB patients the enhanced success rate at the Race game in the food condition was associated with higher attention paid to binge food.

Conclusion

These findings introduce a novel process underlying binges: planning based on backward reasoning is associated with binges. It likely aims to reduce craving for binge foods and extend binge refractory period in BN patients, and avoid binging in ANB patients. Shifts between these goals might explain shifts between eating disorder subtypes.

Can the reinforcing value of food be measured in bulimia nervosa?

Binge eating is a core clinical feature of bulimia nervosa (BN). Enhanced reinforcing value of food may play a role in this behavioral disturbance, but a systematic behavioral assessment of objective measures of the rewarding value of binge eating is lacking. The purpose of this study was to quantify the reinforcing value of food in BN patients as compared with normal controls. A progressive ratio (PR) computerized work task was completed under binge and non-binge instruction. The task consisted of 12 trials. The first trial required 50 keyboard taps to earn one portion of yogurt shake, and subsequent trials required progressive work increments of 200 taps for each additional portion. Completion of all 12 trials required 13,800 taps to earn 2100ml of shake. The breakpoint, defined as the largest ratio completed before a participant stopped working, was the measure of reinforcing efficacy. Ten patients and 10 controls completed the experiment. Under binge instruction, patients completed more trials and taps, and had a higher breakpoint than controls. The non-binge instruction yielded opposite findings; compared to controls, patients completed fewer trials and taps, and had a lower breakpoint. These results support the feasibility and potential utility of a PR task to quantify the reinforcing value of food in patients with BN.

Momentary affect surrounding loss of control and overeating in obese adults with and without binge eating disorder

Research suggests that loss of control (LOC) while eating (the sense that one cannot control what or how much one is eating) is a more salient feature of binge eating than the amount of food consumed. This study examined the unique contributions of LOC and episode size to negative affect surrounding eating episodes in binge eating disorder (BED) and obesity. Twenty-two obese adults with (n = 9) and without (n = 13) BED completed daily records of eating patterns and mood using ecological momentary assessment (EMA). Linear mixed modeling revealed that across groups, greater premeal self-reported LOC was associated with higher premeal negative affect independent of episode size. For individuals with BED, greater premeal self-reported LOC was associated with higher postmeal negative affect, regardless of the amount of food eaten, whereas for obese controls, the combination of LOC and consumption of large amounts of food was associated with lower postmeal negative affect. Results indicate that LOC, but not the quantity of food consumed, is associated with momentary distress related to aberrant eating in BED. Findings also highlight the need for further research investigating the emotional context surrounding aberrant eating in obese individuals without BED.

Gastric compliance in bulimia nervosa

Bulimia nervosa (BN) is a psychiatric illness characterized by eating binges followed by inappropriate behavioral attempts to compensate for the binges, usually vomiting or laxative abuse. Patients with BN have disturbances in the development of satiety during a meal as well as disturbances in functions of the upper gastrointestinal tract such as slowed gastric emptying, impaired gastric accommodation reflex and blunted cholecystokinin release. The present study examined gastric compliance and sensory responses to gastric distention in women with BN and controls. Sixteen women with BN and 13 healthy control subjects swallowed an inflatable bag that was placed in the proximal stomach. The bag was inflated to produce increasing steps of pressure against the stomach wall, before and after consumption of a 200 ml (200 Kcal) liquid meal. Pressure and volume were recorded for 2-min periods, beginning at 0 mm Hg pressure and increasing in steps of 2 mm Hg until subjects reported discomfort, gastric volume reached 600 ml, or pressure reached 20 mm Hg. At each pressure step subjects made sensory ratings. Gastric compliance was calculated as the slope of the best-fit straight line of each subject's gastric volume vs. gastric pressure. There was a significant postmeal increase in gastric compliance in both groups of subjects but there was no difference in compliance between patients with BN and controls. Patients with BN appeared to have diminished sensitivity to gastric distention. In conclusion, although other studies have described gastrointestinal abnormalities associated with BN, the current study found gastric compliance of patients with BN to be normal.

Eating disorders: clinical features and pathophysiology

Anorexia nervosa (AN) and bulimia nervosa (BN) are disorders of eating and weight-related behavior that together afflict some 1-3% of women in the United States. One of the remarkable features about each of the eating disorders is how persistent the disordered eating behavior becomes once it has begun. Substantial psychological, social, and physiological disturbances are associated with eating disorders, and it has been very difficult to disentangle those factors that may result from the disturbed behavior from the factors that may have predisposed individuals to, or precipitated the development of, the disorder. This article will briefly review the definitions, phenomenology, and identified risk factors for development of each of the major eating disorders. Pathophysiology will be discussed, with a particular focus on candidate factors that might sustain disordered eating behavior, as informed by clinical and basic science research. Future research directions will be suggested.

Energy and macronutrient intake in bulimia nervosa

Energy deprivation and malnutrition are often thought to be key factors in the maintenance of bulimia nervosa (BN). Our review shows that it is unclear how much energy is actually available to BN patients' metabolism because the contribution of food consumed during binge eating is generally neglected. Also, there is little evidence for another key hypothesis that binge-eating episodes are triggered by carbohydrate craving. This study examined energy consumption and macronutrient composition of meals and binge-eating episodes in food diaries. Forty female BN patients, 40 female panic disorder (PD) patients, and 40 healthy women recorded their food intake while in their natural environment during two consecutive days. We did not find the expected evidence for chronic energy deprivation and malnutrition in BN patients. Also, there was no evidence that carbohydrate craving drives binge eating. The implications for models of BN and for treatments targeting eating behavior are discussed.

Nutritional interventions for individuals with bulimia nervosa

Many physical and psychological effects of bulimia nervosa are caused by the patient's partial starvation and chaotic nutritional cycle. Attention should thus be initially directed to correcting nutritional deficiencies and abnormal eating patterns, and providing dietary counselling. Nevertheless, very little has been written about the nutritional management of this eating disorder. Nutritional counselling for bulimia patients is reviewed in this paper. Current knowledge about nutritional therapy and its efficacy, goals and objectives is presented, along with recommendations used in treatment programmes. Lastly, the key steps of nutritional management are summarised.

Where should human eating be studied and what should be measured?

Meiselman's (1992) proposal for redirection of research on human eating behavior towards eating in real settings is misdirected, because it does not take into consideration the questions being addressed by laboratory studies. In fact many of the studies for which he has called have in fact been done and will be cited. There is no compelling scientific or strategic reason that investigators who are making good progress on the problem of what controls the amount eaten should be exhorted to examine what controls the place or time of eating or what is selected for eating. They are different problems which require different methodology. The field is large enough for both kinds of studies and there is no reason to berate investigators as Meiselman does for not investigating the problem he happens to be studying.