Development and validation testing of a weight management nutrition knowledge questionnaire for adults

Background/Objectives: Because no validated tool exists to assess nutrition knowledge regarding weight management we developed and tested the Weight Management Nutrition Knowledge Questionnaire (WMNKQ). Subjects/Methods: The questionnaire assesses nutrition knowledge in these categories: energy density of food, portion size/serving size, alcohol and sugar sweetened beverages, how food variety affects food intake, and reliable nutrition information sources. In total 60 questions were reviewed by 6 experts for face validity and quantitative analysis was used to assess item difficulty, item discrimination, internal consistency, inter-item-correlation, test-retest reliability, construct validity, criterion validity, and convergent validity. Results: The final WMNKQ contained 43 items. Experts removed 3 of the original 60 questions and modified 41. Eighteen items did not meet criteria for item difficulty, item discrimination, and/or inter-item correlation; 4 were retained. The WMNKQ met criteria for internal consistency (Cronbach's alpha = 0.88), reliability (test-retest correlation ρ = 0.90, P < 0.0001), construct validity (known groups comparison) - dietitians scored 16% better (p < 0.0001) than information technology workers, and criterion validity (pre- to post-intervention improvement in knowledge scores = 11.2% (95% CI 9.8–12.5, p < 0.0001)). Participants younger than age 55 scored significantly better than those over age 55 (convergent validity). Conclusions: The WMNKQ measures how well nutrition principles of weight management are understood.