How fat will it make me? Estimation of weight gain in anorexia nervosa

Abstract

This study investigates the subjective estimation of weight gain in patients with anorexia nervosa (AN) when being confronted with food cues both in a general (self-unrelated) and in an intent-to-eat (self-related) condition. Looking at the presentation of different snack pictures with different nutrition values (high-low calories), AN patients (N = 24) and age-matched healthy women (N = 27) estimated the weight gain when they imagined eating the presented portions of snack pictures once a day in addition to the normal daily nutrition in the following two conditions: 1) a general condition without specific additional instruction, 2) an intent-to-eat condition, in which they were instructed to imagine that they would eat the snack themselves.

Compared to healthy women, patients with AN estimated a higher weight gain only in the intent-to-eat condition, i.e. when they imagined eating the snacks themselves, but not in the general, not self-related condition. In the patient group, mean estimations of weight gain were associated with the “drive for thinness”. This study suggests cognitive abnormalities related to the effects of food intake on the weight gain in AN, and that these cognitive anomalies could be related to the fear of gaining weight, one central symptom of AN. It appears that the self-reflective disturbed cognition, rather than the general cognition, could be the main driver underlying anorexia and that the overestimation of the energetic content of food is related to the drive for thinness.

Introduction

The restriction of energy intake, the intense fear of gaining weight, and the distorted body image are crucial symptoms of anorexia nervosa (American Psychiatric Association, 2013). The persistence of these symptoms often leads to relapse or to a chronic course of the disease (i.e. (Claudino et al., 2006, Foerde et al., 2015, Mayer et al., 2012, Schmidt and Treasure, 2006, Stice, 2002). The attitude toward nutrition is manifestly altered in anorexia nervosa (AN) patients, and restrictive calories intake has been objectively assessed (Biezonski et al., 2016, Heaner and Walsh, 2013). One of the main symptoms of AN is an intense fear of weight gain even when the own body weight is very low. Patients often mention fear, and hold catastrophic reasoning when it comes to food intake, i.e. believing that they will gain an inappropriate amount of weight after eating food.

AN patients often have special food habits and eating rituals, such as eating very slowly, delaying food intake or cutting the food into very small pieces (i.e. (Claudino et al., 2006, Gianini et al., 2015, Halmi, 2007, Sunday and Halmi, 1996).). These behaviors suggest that the beliefs preceding food ingestion could represent an important aspect of the eating restriction in AN. Studies using pictorial food stimuli suggest disturbed processing food cues in AN patients (Giel, Teufel, et al., 2011), but the pathological choice of low-calorie food remains - although stereotyped – largely unclear (Steinglass & Walsh, 2016). Plausibly, the pathological eating habits in AN could in some way be related to the fear of gaining weight (Foerde et al., 2015). A recent study (Kissileff et al., 2016 #5311) investigated the expected anxiety related to the maximum tolerated portion size in AN-patients and control subjects, and reported that the expected anxiety response was greater for patients compared to healthy control, but in this study the anxiety was not explicitly related to the putative weight gain.

To investigate the relationship between food ingestion and the postulated weight gain could help to better understand the mental process of the illness. Thus, testing the expectations about one's own weight gain while being faced with calories intake seems a suitable way for investigating the pathological beliefs leading to the dysfunctional eating behavior in AN. This pilot study examines the estimation of weight gain after the imagined intake of different snacks once a day in addition to individual normal daily meals in female AN patients, and in an age-matched control group of healthy women, under a general - not self-related - condition and an “intent-to-eat” – self related - condition, in which the participants were instructed to estimate the increase in weight gain while imagining that they themselves would eat the pictured snack. We hypothesized that, 1) a higher weight gain would be estimated for every kind and size of snack in AN compared to the control group, 2) AN patients would estimate a higher weight gain than the control group in the intent-to-eat condition. 3) This effect would be stronger for high caloric and larger snacks. Finally, as the intense mental preoccupation with food and the overestimation of weight gain are psychopathological signals of illness severity, we expected a positive correlation between the estimated weight gain, and some parameters of the severity of the illness.