- We examined the effect of body norms on ideal and current body size perception. In Study One, female participants were randomly assigned to one of three experimental conditions: (1) a thinner body norm, (2) a heavier body norm, or (3) no body norm. Body norms were manipulated by indicating a bogus "population average," and current and ideal body size perception were subsequently measured using a body silhouettes measure. Women had a thinner ideal body size in the thinner norm condition than in the heavier norm condition. Study Two replicated these results, but in a sample of young men and with regards to muscularity rather than thinness. Men had a more muscular ideal body size in the more muscular norm condition than in the less muscular norm condition. Current body size perception was also influenced by body norms, but only for women and after controlling for BMI.