Social norms, ideal body weight and food attitudes.

This paper uses French data on ideal body weight and food attitudes to analyse the role of social norms in the individual's weight control problem. A proxy measure of social norms is calculated by averaging individual perceptions of the ideal Body Mass Index (BMI) over all observations within a reference group. Testing for different definitions of the reference group, we find that individual representations of ideal body shape are differentiated mainly along gender and age lines. Social norms regarding body shape have a significant effect on perceptions of ideal BMI only for those women who want to lose weight, with an elasticity close to 0.5. For many women and for all men, ideal BMI is almost exclusively determined by habitual BMI. Last, ideal BMI predicts a number of attitudes towards food, while social norms do not. These results suggest that promoting medical norms regarding body shape should have little effect on individual food attitudes.