The estimation of body mass index and physical attractiveness is dependenton the observer's own body mass index

A disturbance in the evaluation of personal body mass and shape is a key fe ature of both anorexia and bulimia nervosa. However, it is uncertain whethe r overestimation is a causal factor in the development of these eating diso rders or is merely a secondary effect of having a low body mass. Moreover, does this overestimation extend to the perception of other people's bodies? Since body mass is an important factor in the perception of physical attra ctiveness, we wanted to determine whether this putative overestimation of s elf body mass extended to include the perceived attractiveness of others. W e asked 204 female observers (31 anorexic, 30 bulimic and 143 control) to e stimate the body mass and rate the attractiveness of a set of 25 photograph ic images showing people of varying body mass index (BMI). BMI is a measure of weight scaled for height (kg m(-2)). The observers also estimated their own BMI. Anorexic and bulimic observers systematically overestimated the b ody mass of both their own and other people's bodies, relative to controls, and they rated a significantly lower body mass to be optimally attractive. When the degree of overestimation is plotted against the BMI of the observ er there is a strong correlation. Taken across all our observers, as the BM I of the observer declines, the overestimation of body mass increases. One possible explanation for this result is that the overestimation is a second ary effect caused by weight loss. Moreover, if the degree of body mass over estimation is taken into account, then there are no significant differences in the perceptions of attractiveness between anorexic and bulimic observer s and control observers. Our results suggest a significant perceptual overe stimation of BMI that is based on the observer's own BMI and not correlated with cognitive factors, and suggests that this overestimation in eating-di sordered patients must be addressed directly in treatment regimes.