The weights of insured persons are not representative of the weights of the general population; they appear to be appreciably lower. This is particularly marked in the case of women. The trend toward decreasing weight in insured women is contrary to the actual trend toward increasing weight of women in the general American population. The reason for these differences may be sought in part in the self-selection of persons applying for insurance under ordinary policies, and in part in the selective process applied by life insurance companies in the issuance of these policies.
Seltzer CC, Mayer J. How Representative Are the Weights of Insured Men and Women?. JAMA. 1967;201(4):221-224. doi:10.1001/jama.1967.03130040017005