Does Sex Matter in the Link Between Self-Efficacy and Mediterranean Diet Adherence in Adolescents? Insights from the EHDLA Study

<b>Background/Purpose:</b> To our knowledge, no previous study has analyzed the associations between self-efficacy and adherence to the Mediterranean diet (MedDiet) in adolescents, nor have sex-based differences in this relationship been examined. The aim of the current study was to examine the relationship between self-efficacy and MedDiet adherence in Spanish adolescents. <b>Methods:</b> This research was cross-sectional and involved 619 adolescents (56.5% girls) who were part of the Eating Habits and Activities of Daily Living (EHDLA) project. Self-efficacy was assessed using a 10-item scale (general self-efficacy scale), which yielded scores ranging from 20 to 100 points. The Mediterranean Diet Quality Index for Children and Adolescents (KIDMED), which consists of a 16-item questionnaire with scores ranging from -4 to 12, was used to evaluate adherence to the MedDiet. Unhealthy behaviors related to the MedDiet were assigned a score of -1, whereas healthy behaviors received a score of +1. <b>Results:</b> Overall, for each 20-point increase in self-efficacy, boys had a greater non-significant likelihood of having optimal MedDiet adherence (1.33%, 95% confidence interval [CI] -5.15 to 7.82, <i>p</i> = 0.687). Conversely, girls had a greater significant likelihood of having optimal MedDiet adherence per further point in self-efficacy (7.40%, 95% CI 2.28 to 12.53, <i>p</i> = 0.005). Individually, among boys, a 20-point increase in self-efficacy was associated with a 4.8% higher probability of having a dairy product for breakfast (95% CI 0.2 to 9.4, <i>p</i> = 0.042). Among girls, the same increase in self-efficacy was linked to a greater probability of consuming fruit or fruit juice daily (6.8%, 95% CI 2.2 to 11.4, <i>p</i> = 0.004), eating a second fruit every day (8.6%, 95% CI 3.4 to 13.8, <i>p</i> = 0.001), consuming fish regularly (6.2%, 95% CI 1.1 to 11.2, <i>p</i> = 0.017), enjoying pulses and eating them more than once a week (4.5%, 95% CI 0.3 to 8.8, <i>p</i> = 0.035), having cereals or grains for breakfast (5.4%, 95% CI 0.4 to 10.5, <i>p</i> = 0.035), and regularly consuming nuts (5.2%, 95% CI 0.2 to 10.2, <i>p</i> = 0.041). Additionally, increases in self-efficacy was associated with a 5.0% lower probability of skipping breakfast (95% CI -8.8 to -1.1, <i>p</i> = 0.012). <b>Conclusions:</b> Our results revealed a significant association between self-efficacy and MedDiet adherence among girls, whereas the relationship between self-efficacy and the MedDiet in boys was not significant. These results suggest that interventions aimed at improving adolescent dietary patterns should consider incorporating strategies to increase self-efficacy, potentially with sex-specific approaches.