Over the past decades, the prevalence of obesity has markedly increased worldwide. Stress is recognized as a substantial contributor to increased body weight; therefore, stress management interventions, especially cognitive behavioural, are becoming increasingly popular. The impact of stress management on stress- and obesity-related biomarkers (eg blood lipid profile, HBA1c, inflammatory biomarkers, such as CRP) has been scarcely studied. The aim of this study was to assess the effect of a novel cognitive behavioural stress management intervention, called 'Pythagorean Self-Awareness Intervention' (PSAI), in overweight/obese adults. This was a two-armed 1:1 randomized, nonblind controlled study including overweight/obese individuals. The control group followed a personalized Mediterranean low-calorie diet, and the intervention group followed the same diet in addition to the PSAI intervention for 8weeks. Measurements included demographic, anthropometric (ie BMI, waist-to-hip ratio), stress (ie perceived stress, salivary cortisol), dietary behaviour (ie emotional eating) and metabolic parameters (ie blood lipid profile, HBA1c, CRP, body composition in fat and water). Outcome per-protocol analysis was performed using mixed linear models adjusted for age and gender. A total of 49 of 62 eligible adults were analysed in the study (there were three dropouts in the intervention group and 10 dropouts in the control group); 28 were assigned to the intervention group (mean age 54.7±11.9years) and 21 to the control group (mean age 51.8±11.9years). The intervention group showed a statistically significant decrease in perceived stress, cortisol concentrations 30minutes after awakening, cortisol's area under the curve, BMI, waist-to-hip ratio, restrained, emotional and external eating behaviour, fasting glucose, LDL, triglycerides, HbA1c and body and trunk fat, compared with the control group. Based on the observed effect sizes, clinically meaningful changes may be more evident in stress perception, restrained and external eating behaviour, Hb1ac and trunk fat. The compliance to the PSAI intervention reached 100%, and there were no adverse effects. The PSAI technique may be an effective stress management method for overweight/obese adults. Future and larger randomized controlled studies are needed to allow generalization of these findings.