Relationship between dieting to lose weight and the functioning of the central executive.

The study investigated the impact of weight-loss dieting on the four identified functions of the central executive of working memory: dual-task performance, random generation, task switching and activation of long-term memory. Participants were 32 female current dieters and 32 female non-dieters who completed four well-established cognitive tasks designed to tap each specific function. Participants also completed tasks designed to load on the phonological loop and visuo-spatial sketch pad working memory systems, as well as self-report measures of depressed affect and preoccupying cognitions. Dieters performed more poorly than non-dieters on all central executive measures except random generation. These dieting-related differences were most evident on moderately complex trials, and were partially mediated by preoccupying thoughts about food, weight and body shape, but not by BMI or depressed affect. It was concluded that weight-loss dieting has a relatively global impact on central executive functioning and thus has wide-ranging cognitive consequences.