Obesity is not inlcuded in eating disorders characterized by the DSM-IV classification of the American Psychiatry Association. Current clinical diagnosis depends on body mass index (BMI). Although it was not evaluated among eating disorders, it presents psychological characteristics seen commonly in eating disorders. Characteristics related with eating disorders such as low self-esteem, body dissatisfaction, perfectionistic attitudes, impulsivity and disinhibition have also been observed in obese patients (1,2). Obese patients are divided into two subgroups, with or without binge eating disorder (BED). Body weights of subjects with binge eating disorder are related to their overeating and psychopathologies, especially depression, are more frequent compared to the other group.
Aggressiveness and anger are involved in significant psychopathological characteristics common in patients with eating disorders (3). Some researchers suggested that impaired eating behavior is related to low self-esteem and high self-directed hostility. Problems about revealing their anger were detected among these individuals. Besides, problems in controlling the expression of anger, accompanying impulsive explosive behaviors are also present (4).
The current status of obesity treatment is not satisfactory. Some treated individuals regain the lost weight in a short time (5). Many researchers are investigating approaches to keep off the lost weight with treatment strategies to lose weight. In previous reports, it has been demonstrated that most obese individuals returned back to their basal BMIs or to higher values within 1-5 years (6). Nowadays, the question is 'What is the difference between the ones who keeps off the weight they lose and those who do not?'. Impulsivity is the possible predictor of relapse in obesity treatment (5). Obese subjects are suggested to be more impulsive than lean ones. Impulsive characteristics are higher in obese patients with BED (7). Impulsive people appear to have no control over their behaviors on eating and they have more interest in food with higher calories. Impulsivity is also considered as a predicting factor among patients who quit treatment. In a survey among the children between the ages of 8-12 years in the Netherlands, impulsivity was measured by behavior and the results of treatment were evaluated. As a result, it was demonstrated that impulsive children lose less weight compared to the others. It was also concluded that impulsive children are more prone to eating delicious foods; therefore more attention should be given to their dietary control (5).
Another issue supporting the relationship between obesity and impulsivity is the occurrence of obesity in children with attention deficiency and hyperactivity disorder (ADHD) (8). ADHD was detected in most of the children (58%) who were receiving obesity treatment. Also, the BMI of children with ADHD was higher than the control group (9). In addition, there is evidence for decreased levels of D2 receptors in the striatum of obese subjects (10-13). With regard to the therapeutic implications, recent studies indicate that methylphenidate (MPH), a drug widely used for ADHD, reduced overall energy intake with a selective reduction in dietary fat (14,15). Dopamine (DA) exerts neuromodulatory inşuences over behavior and cognition via the fronto-striato-cerebellar circuitry and pharmacotherapy is thought to target these systems to ameliorate problems with impulsivity, inattention and hyperactivity. To explain the comorbidity of ADHD and obesity, it has been hypothesized that a predisposition to glucose starving and obesity is due to inadequate dopaminergic activity in the reward center of the brain. Consumption of large quantities of carbohydrates (carbohydrate binging) stimulates production and usage of dopamine within the brain and it results in a kind of therapeutic effect (16,17).
All this information should guide the planning of treatment. Specific cognitive behavioral approaches developed for the treatment of impulsive behavior could contribute much to the treatment of obesity(18).