Purpose <p>This study aimed to examine the association between sustainable and healthy eating behaviors (SHEB) and obesity indicators, body mass index (BMI) and waist circumference (WC), and to evaluate the mediating and moderating roles of food addiction (FA) in these relationships.</p> Methods <p>This cross-sectional study was conducted between June 2024 and February 2025 with 4234 adults aged ≥ 18&#xa0;years. Anthropometric measurements were obtained using standardized procedures. SHEB and FA were assessed using validated instruments. All analyses were conducted using the SPSS package program, PROCESS Macro and JASP Statistical Software.</p> Results <p>In adjusted models, each one-unit increase in FA symptom count was positively associated with BMI (β = 0.103, <i>p</i> &lt; 0.001) and WC (β = 0.030, <i>p</i> = 0.029). Overall SHEB scores showed a small positive association with BMI, whereas no association was observed with WC. SHEB subcomponents related to diet quality, including healthy and balanced diet, preference for local foods, and low-fat choices, were inversely associated with both BMI and WC (<i>p</i> &lt; 0.05), whereas seasonal food consumption and avoidance of food waste were positively associated with obesity indicators. FA showed a statistically significant but very small indirect effect in the association between SHEB and BMI (indirect effect = 0.0004; 95% CI: 0.000–0.001), while no indirect effect was observed for WC. Moderation analyses revealed that FA significantly modified the SHEB-BMI relationship (<i>p</i> for interaction = 0.003), with stronger associations observed at moderate and high FA levels.</p> Conclusions <p>Sustainable and healthy eating behaviors are not uniformly associated with lower obesity risk and appear to interact with FA-related behaviors. Accounting for addictive-like eating behaviors may be critical for improving the effectiveness of sustainable nutrition strategies in obesity prevention and public health interventions.</p>