Obese adults have visual attention bias for food cue images: evidence for altered reward system function

Background: The major aim of this study was to investigate whether the motivational salience of food cues (as reflected by their attention-grabbing properties) differs between obese and normal weight subjects in a manner consistent with altered reward system function in obesity. Methodology/Principal Findings: 18 obese and 18 normal weight, otherwise healthy, adult females between the ages of 18-35 participated in an eye-tracking paradigm in combination with a visual probe task. Eye movements and reaction time to food and nonfood images were recorded during both fasted and fed conditions in a counterbalanced design. Eating behavior and hunger level were assessed by self-report measures. Obese individuals had higher scores than normal weight individuals on self-report measures of responsiveness to external food cues and vulnerability to disruptions in control of eating behavior. Both obese and normal weight individuals demonstrated increased gaze duration for food compared to nonfood images in the fasted condition. In the fed condition however, despite reduced hunger in both groups, obese individuals maintained the increased attention to food images, while normal weight individuals had similar gaze duration for food and nonfood images. Additionally, obese individuals had preferential orienting towards food images at the onset of each image. Obese and normal weight individuals did not differ in reaction time measures in the fasted or fed condition. Conclusions/Significance: Food cue incentive salience is elevated equally in normal weight and obese individuals during fasting. Obese individuals retain incentive salience for food cues despite feeding and decreased self-report of hunger. Sensitization to food cues in the environment and their dysregulation in obese individuals may play a role in the development and/or maintenance of obesity