Who are you trying to fool: does weight underreporting by dieters reflect self-protection or self-presentation?

Nutritionists are well aware that people tend to underreport their weights, but psychologists still often rely on weight self-reports. The present paper reviews research on weight underreporting and attempts to identify its underlying motivations. Restrained eaters (and overweight individuals) are especially likely to underreport their weight. We examine potential reasons for such underreporting in these groups, including (1) perceptual biases that make people misperceive body weight; (2) an impression-management/self-presentation strategy (telling others that one has a more socially desirable weight); or (3) self-protection, with underreporting allowing one to protect self-esteem by convincing oneself that one is thinner than is really the case. The evidence indicates that overweight and restrained women underreport their weight in an attempt to protect themselves. The consistent and motivated underreporting of weight by restrained eaters not only illuminates their psychological functioning, but indicates a bias that may be problematic for research that relies on self-reports.