Impact of a Behavioral Lifestyle Intervention on Dietary Habits, Anthropometric and Psychological Outcomes, and Biomarkers of Oxidative Stress and Telomere Length in Adults

Background/Objectives: Lifestyle-related behaviors and chronic stress are key determinants of metabolic health, psychological well-being, and biological aging. Structured behavioral interventions that enhance self-awareness and self-regulation may promote sustained improvements across multiple health domains. This study aimed to evaluate the effects of a six-week Pythagorean Self-Awareness Intervention (PSAI) on dietary habits, anthropometric and psychological outcomes, and biomarkers of oxidative stress and telomere length in adults. Methods: This quasi-experimental pre–post intervention study included 30 apparently healthy adults. Participants underwent baseline assessments followed by a six-week Pythagorean Self-Awareness Intervention (PSAI) and were reassessed post-intervention. Outcomes included Mediterranean diet adherence (MedDiet Score), anthropometric and body composition measures, validated psychological questionnaires (PSS-14, DASS-21, RSES, HLPCQ, HLC, STAXI, SSGS, PSQI), cognitive performance (SDMT, CVLT-II, BVMT-R), serum oxidative stress and antioxidant capacity, and leukocyte telomere length (T/S ratio). Statistical analyses were performed using paired-samples Student t-tests or Wilcoxon signed-rank tests, with significance set at p < 0.05. Results: Significant improvements were observed in Mediterranean diet adherence (p = 0.001), along with reductions in body weight, BMI, waist and hip circumference, and intermuscular adipose tissue (all p < 0.05). Psychological outcomes improved significantly, including reduced perceived stress (PSS-14, p = 0.004) and depressive symptoms (DASS-21, p = 0.005), and improved self-esteem (RSES, p = 0.003) and sleep quality (PSQI, p < 0.001). Cognitive performance improved across all domains, including information processing speed, verbal learning, and visuospatial memory (all p < 0.05). Regarding biological markers, oxidative stress decreased (p = 0.023), and antioxidant capacity (p = 0.009), and leukocyte telomere length increased (p < 0.001), indicating improved redox balance and cellular aging profiles. Conclusions: The six-week Pythagorean Self-Awareness Intervention (PSAI) was associated with significant improvements in dietary habits, anthropometric and psychological outcomes, cognitive performance, and biomarkers of oxidative stress and telomere length. These findings suggest that participation in a structured self-awareness-based intervention was associated with multidomain improvements in this cohort. However, given the quasi-experimental design without a control group, these findings should be considered preliminary and require confirmation in adequately powered randomized controlled trials.