The RESILIENT project is a clinical trial investigating leptin sensitivity in both children and adults with overweight or obesity. The study examines the additive effects of Cognitive Training (CT) and Social Training (ST) on leptin sensitivity, compared to stand-alone Intensive Health Behaviour Treatment (IHBT), which includes diet and Physical Activity (PA). The intervention will last for 8 weeks, followed by a 12-week washout period. A multilevel assessment will be conducted, evaluating in vivo leptin sensitivity (through the ratio of leptin levels to caloric intake) as well as ex vivo molecular analysis of leptin signaling in Peripheral Blood Mononuclear Cells (PBMCs). Additionally, clinical, psychological, cognitive, and physiological assessments will be performed to assess the efficacy of each intervention. By investigating leptin resistance as a potential molecular bridge between metabolic dysregulation and cognitive dysfunctions, this study may contribute to the development of more effective, long-term treatments for obesity and overweight. Additionally, in vivo investigation of leptin sensitivity may be particularly important for providing evidence of the metabolic and cognitive effects necessary for developing novel anti-obesity treatments.