Associations between diet quality and obesity in a nationally representative sample of Iranian households: A cross-sectional study

Objective: Research examining associations between diet quality and obesity in Iranian adults is limited by small and non-representative samples. This study examined associations between two diet quality indices and obesity risk in a nationally representative sample of Iranian adults and interactions by sex and area of residence. Methods: Data on 18,307 adults (mean age 37 [SD 15.2] years) were used from the Iranian National Survey 2001-2003. Two diet quality indices (Healthy Eating Index 2015, HEI-2015, and Diet Quality Index International, DQI-I) were calculated from household 24-h dietary recalls. Multi-level regression analyses were used to examine the association between household diet quality and individual-level obesity risk, with interaction terms for sex and area of residence. Results: Higher household HEI-2015 and DQI-I were associated with higher risk of obesity (HEI-2015: relative risk ratio: 1.04, 95% CI: 1.03, 1.05; DQI-I: relative risk ratio: 1.02, 95% CI: 1.01, 1.02), with stronger effect sizes in adults living in rural areas. Conclusions: Higher diet quality (HEI-2015 and DQI-I) was associated with higher obesity risk, which was stronger in adults living in rural areas. Due to the complexity of examining these associations in a Middle Eastern country undergoing a nutrition transition, longitudinal research is needed to confirm these findings.