Accuracy in estimating the body weight of self and others: Impact of dietary restraint and BMI

We examined the accuracy of people's estimates of their own body weight and of the body weight of other people. Female undergraduates (n = 132) self-reported their weight, were weighed by the experimenter, and completed a measure of dietary restraint. Participants also viewed 10 photographs of women ranging from underweight to obese and estimated their body weight. Individuals high in dietary restraint underestimated their own weight to a greater extent than those low in dietary restraint, but this effect was accounted for by individual differences in BMI: heavier participants underestimated their weight to a greater extent than leaner participants. Participants also underestimated the weight of heavier targets to a greater extent than they did leaner targets, but the degree of inaccuracy was not related to participants’ dietary restraint or BMI. These findings support the hypothesis that inaccuracies in self-reported weight reflect deliberate misreporting rather than a cognitive or perceptual bias.

► Dietary restraint is related to greater underestimation of one's own weight. ► BMI accounts for the effect of dietary restraint on errors in self-reported weight. ► The weight of heavier targets was underestimated more than that of leaner targets. ► Errors in self-reported weight were unrelated to errors in gauging targets’ weight.