Validation of the Household Food Waste Questionnaire (HFWQ) in an Iranian urban setting (Tehran)

Household food waste poses a significant global challenge with considerable economic, environmental, and social consequences. Accurate measurement is essential for developing effective policies to reduce food waste. This study aimed to translate, culturally adapt, and validate the Household Food Waste Questionnaire (HFWQ), adapted from the REFRESH instrument, for use in an Iranian urban setting. The original instrument was translated into Farsi, back-translated, and adapted to reflect local dietary habits. Content validity was evaluated by a panel of 17 experts in nutrition and related fields, who reviewed the questionnaire for clarity and relevance, and face validity was assessed qualitatively with members of the target community. Criterion validity was assessed by comparing questionnaire estimates with weekly weighed edible food waste data from 50 households ( n = 50), as the gold standard. The results showed a statistically significant but moderate correlation between the questionnaire-based estimates and the weighed method ( r = 0.431, p = 0.002). On average, self-reported estimates captured about 43% of the directly weighed edible food waste, consistent with the known underestimation of self-reports. Accordingly, the adapted HFWQ is best suited for assessing relative differences and monitoring changes in household food waste across urban Iranian settings, rather than for precise absolute quantification.