Development and validation of a Weight Literacy Scale in English and Spanish.

Objectives: To develop and validate a Weight Literacy Scale in English and Spanish for adults.

Methods: The two-phase study utilized quantitative and qualitative methods. Phase 1 of the study consisted of developing an initial survey (English and Spanish versions) assessing weight literacy based on a review of the literature; conducting semi-structured interviews with content experts (N = 9) to refine survey items; and conducting in-person cognitive interviews with 20 study participants (N = 10 English-speaking and N = 10 Spanish-speaking adults) for survey pre-testing. Survey items were modified based on Phase 1 findings. Phase 2 consisted of a psychometric study of the Weight Literacy Scale developed in Phase 1. Procedures included administering the Weight Literacy Scale to 200 study participants (N = 100 English-speaking and N = 100 Spanish-speaking adults), a quantitative survey assessing dietary and physical activity behaviors and sociodemographics, measuring participants' height and weight, and assessing the scale's validity and internal reliability. A subset of Phase 2 participants (N = 71) completed the weight literacy scale at two-weeks follow-up to assess test-retest reliability. Participant recruitment and study procedures took place in community settings in central Massachusetts for both study phases. Weight literacy scale scores were calculated as the sum of total correct items. Three rounds of factor analysis were performed to identify items for elimination. The Kuder Richardson's Coefficient of reliability was calculated. Correlations between the Weight Literacy Scale scores and related measures (body mass index and weight status, dietary behaviors, physical activity behaviors, and confidence in filling out medical forms) were examined.

Results: The final scale included 31 items and demonstrated strong internal consistency (Kuder Richardson Coefficient = 0.90), reasonable construct validity, and acceptable test-retest reliability (ρ = 0.72).

Conclusion: The Weight Literacy Scale is a reliable and valid research instrument to assess weight literacy among English- and Spanish-speaking adults.