چقدر باید بخورم؟ برآورد وعده غذایی در بی اشتهایی عصبی

Pathological concern regarding one’s weight and weight gain is a crucial feature of anorexia nervosa. Consequently, anorexia nervosa patients often claim that they are uncertain regarding the amount of food they should eat. The present study investigated whether individuals with anorexia nervosa show an altered estimation of meal portion sizes and whether this estimation is modulated by an intent-to-eat instruction (where patients are asked to imagine having to eat the presented meal), meal type and meal portion size. Twenty-four women with anorexia nervosa and 27 healthy women estimated, using a visual analogue scale, the size of six different portions of three different meals, with and without intent-to-eat instructions. Subjects with anorexia nervosa estimated the size of small and medium meal portions (but not large meal servings) as being significantly larger, compared to estimates of healthy controls. The overestimation of small meal portions by anorexia nervosa subjects was significantly greater in the intent-to-eat, compared to general, condition. These findings suggest that disturbed perceptions associated with anorexia nervosa not only include interoceptive awareness (i.e., body weight and shape), but also extend to external disorder-related objects such as meal portion size. Specific therapeutic interventions, such as training regarding meal portion evaluation, could address these difficulties.

Anorexia nervosa (AN) is a potentially life-threatening eating disorder (ED) that primarily affects young women. DSM-IV (American Psychiatric Association, 2000) lists four criteria for the diagnosis of an AN: (1) Refusal to maintain body weight at or above a minimally normal weight for age and height; (2) intense fear of gaining weight; (3) disturbance of one’s body weight or shape; and (4) amenorrhea. Clinical observation suggests that AN patients have difficulty estimating food portion size. AN patients frequently claim that at the beginning of the illness, typically after dieting or other food intake restriction, they lost the capacity to reliably evaluate food amounts. In particular, they became unsure about their estimates regarding the size of food portions they intended to eat. The ability to visually evaluate food amounts has received little attention in AN research. Improving restrictive eating behavior and normalizing eating habits are especially important to the treatment of AN. Improved understanding of how visual evaluation of food amounts contributes to the disorder will facilitate the development of more effective treatment strategies for AN. In a previous study, individuals with AN were found to exaggerate their estimates of the size of high-energy food objects (e.g., picture of a box of 200 g chocolate biscuits), compared to equally sized non-food objects (e.g., picture of a jewellery box), to a greater extent than healthy controls, suggesting abnormal visual perception of high-energy food objects in AN (Yellowlees, Roe, Walker, & Ben-Tovim, 1988). In contrast, estimates of the number of food objects (a plate filled with 27 candies) and non-food objects (a plate filled with 27 LEGO® bricks) did not differ between AN patients and healthy controls (Vinai et al., 2007). The present study was designed to investigate whether estimates of meal portion sizes differ between AN patients and healthy controls. Given that individuals with AN have difficulty eating adequate portions of food, we predicted that their estimates of food amounts, as depicted in pictures of real meals, would differ from estimates obtained from normal individuals. Clinical observation suggests that the salience of food changes for AN patients during actual meal situations. In accord with this observation, we examined the influence of intent-to-eat instruction (“imagine eating the presented meal”) on estimates of meal portion size. The present study also examined the potential influence of affective state on estimates of meal portions, given evidence that AN patients experience increased anxiety when viewing food pictures or high calorie drinks (Ellison et al., 1998 and Friederich et al., 2006).