Chapter 8: Behavioral Determinants of Obesity

INTRODUCTION

Behavioral determinants of obesity have been widely studied in the field of psychology, leading most to conclude that it is a complex condition that is difficult to treat with long-term success. This chapter reviews the most common theories about psychological causes of obesity, the co-occurrence of obesity and common mental disorders, and psychological treatment options for obesity and binge-eating disorder (BED). Suggestions for assessment and treatment planning are provided to help physicians determine the presence of underlying psychopathology or problematic behavior patterns and to work with their obese patients to find a program best suited to their individual psychological needs.

THE ETIOLOGY OF OBESITY: PSYCHOLOGICAL FACTORS

It is widely accepted that the etiology of obesity is multidetermined. In addition to genetic, physical, environmental, and cultural/sociological factors, psychological research has focused on individual characteristics such as personality, systems of reinforcement, cognitive processes, and developmental history, as well as the interplay of all of these factors. Decades of research have focused on the psychology of overeating and whether obese individuals differ from their nonobese counterparts in their eating behavior.¹ In the following section, the most studied theories about overeating in obesity are presented along with discussion of their current research support.

A commonly held view is that obese people are more likely to engage in emotional eating, using food to manage distressing or overwhelming affect. The psychosomatic hypothesis, first put forth by Kaplan and Kaplan² suggests that obese individuals likely learned as children to overeat as a way to self-soothe when anxious. Their subsequent weight gain further increases negative affect, which then leads to more overeating and obesity. The psychoanalyst Hilde Bruch³ further hypothesized that for these individuals early developmental trauma, such as poor infant-caregiver attunement, interferes with the child’s ability to distinguish between internal sensations of hunger and uncomfortable emotional states. The child therefore misinterprets emotions such as sadness and anger as hunger and will overeat to regulate these feelings.³

In their 2002 review, Canetti, Bachar, and Elliot⁴ concluded, that for both obese and nonobese people, the presence of negative emotions (e.g., anger, sadness, boredom) leads to increased food consumption. Some research indicated that positive emotions (e.g., joy) can also increase food intake for both obese and nonobese individuals; however, the support for this conclusion is not as robust.⁴ Canetti et al.⁴ stated that the psychosomatic theory of obesity has received enough research support to conclude that obese individuals and dieters (obese or normal weight) are more likely to engage in emotional eating. A more recent review of binge eating and overeating in laboratory settings further supported the role of negative affect as a trigger for overeating for obese individuals, and even more strongly so for those with BED.⁵

In the late 1960s and early 1970s, Schacter argued against the psychosomatic model by developing his externality ...