Background/Objectives: Despite its well-established health benefits, adherence to the Mediterranean lifestyle (MedLife) has declined globally, including in its region of origin, alongside a significant shift toward ultra-processed food consumption. Understanding the factors associated with MedLife adherence is essential for developing targeted interventions and tailored policy recommendations. As part of the MEDIET4ALL PRIMA project, this cross-sectional study aimed to comprehensively examine geo-demographic, socio-economic, psychological, behavioral, and barrier-related factors associated with and potentially contributing to MedLife adherence. Methods: Data were collected from 4010 participants aged 18 years and above across ten Mediterranean and neighboring countries using the multinational MEDIET4ALL e-survey, which included the validated MedLife index, along with various other questionnaires. Results: Results indicate that only 22% of respondents demonstrated high adherence to the Mediterranean lifestyle (MedLife), with significant variability observed across countries, age groups, education levels, and health statuses. Spain had the highest proportion of participants with high adherence (38%). Factors associated with significantly higher adherence rates include older age, living in the Mediterranean region, higher education levels, a greater awareness of MedLife principles, lower perceived barriers, normal BMI, better health status, and stable economic and marital conditions (p-values ranging from 0.04 to <0.001). Additionally, individuals with high MedLife adherence exhibited more socially and physically active lifestyles and experienced less psychological strain (p < 0.001). Regression analyses identified MedLife awareness as the strongest positive predictor of adherence (β = 0.206), followed by social participation (β = 0.194) and physical activity (β = 0.096). Additional positive contributors include life satisfaction, sleep quality, living in the Mediterranean region, age, and education (β ranging from 0.049 to 0.093). Conversely, factors that are negatively associated with adherence include sedentary behavior, living environment, and barriers such as low motivation, taste dislike, price unaffordability, limited availability, and the time-consuming nature of preparing Mediterranean food (MedFood; β ranging from −0.036 to −0.067). Conclusions: These findings indicate that fewer than one in four adults across Mediterranean and neighboring countries demonstrate high adherence to MedLife, supporting prior evidence of suboptimal adherence even within Mediterranean regions. This study identified a range of behavioral, socio-demographic, and environmental factors—both positive and negative predictors—that can help guide the design of targeted, culturally adapted interventions to promote MedLife behavior. Future research should incorporate objective measurements and longitudinal monitoring to better understand underlying mechanisms, establish causality, and develop sustainable strategies for enhancing MedLife adherence in diverse populations.

The Mediterranean Diet (MD) is recognized for its nutritional quality, health-promoting properties, and richness in bioactive compounds, yet studies analyzing complete traditional recipes considering both extractable and non-extractable fractions are limited. This study characterized the total antioxidant capacity (TAC) and phenolic profile of 56 traditional MD recipes from eight countries, grouped into European Mediterranean (France, Italy, and Spain), African Mediterranean (Tunisia, Algeria, and Morocco), and non-Mediterranean European (Luxembourg and Germany) regions. Samples were freeze-dried and subjected to aqueous-organic extraction followed by acid hydrolysis. TAC was measured using TEAC, ORAC, and total phenolics (Folin–Ciocalteu, reflecting reducing capacity), while phenolic profiles were analyzed by HPLC-DAD. Relationships between phenolics and TAC were evaluated using linear and mixed-effects models, accounting for country-level heterogeneity. Mediterranean recipes showed higher TAC and greater phenolic diversity than non-Mediterranean recipes, with a predominance of phenolic acids, secoiridoids, and flavonoids, reflecting characteristic olive oil use. In all regions, the non-extractable fraction contributed >80% to TAC, highlighting underestimation by conventional methods and its dominant contribution to dietary antioxidant intake. TEAC was positively associated with extractable phenolics, whereas ORAC reflected country-specific culinary features independently of total phenolic content. These findings underscore the significant bioactive potential of traditional MD recipes, which can be considered functional foods, and the importance of comprehensive evaluations of both extractable and non-extractable fractions for nutritional research and dietary interventions.