An experiment proved that whether we are happy or not with our appearance affected our intellectual functioning.
A study of approx. 390 participants showed that those who feel better about their body (wearing sweaters) performed better on math tests.
The second group tested swimsuits.
Hebl, M., King, E., & Lin, J. (2004). The swimsuit becomes us all: Ethnicity, gender, and vulnerability to self-objectification. Personality and Social Psychology Bulletin.