Impaired cognitive functioning during spontaneous dieting.

In one of a continuing series of studies, the cognitive performance of normal weight female dieters was compared on two sessions, 3 weeks apart. Those who reported themselves as being on a weight-reducing diet on only one of the two sessions displayed poorer vigilance performance, slower reaction times and poorer immediate recall of words when they were dieting. In contrast, performance on a low processing load tapping task was unaffected. Self-report measures showed that dietary restraint, but not state anxiety or depression was increased during dieting. These results are interpreted in terms of an association between dieting behaviour and high levels of distractibility, and extend earlier findings by demonstrating that these deficits in cognitive performance are closely related to dieting or the perceived need to diet per se.