The goal of this clinical trial is to evaluate whether Mediterranean diet can help manage body weight and improve body composition in adult Parkinson's disease patients who have undergone bilateral subthalamic nucleus deep brain stimulation (STN DBS). The main questions it aims to answer are: Does adherence to the Mediterranean diet for three months post-surgery help control body weight gain in STN DBS patients? Does the Mediterranean diet positively affect body composition and other clinical parameters such as nutritional status, appetite, quality of life, and physical activity? Researchers will compare an intervention group following the Mediterranean diet with a control group continuing their usual diet to see if dietary guidance leads to improvements in weight management, body composition, and other nutritional status parameters. Participants will: Be randomized into intervention and control groups. Receive Mediterranean dietary recommendations (intervention group) or continue usual diet (control group). Undergo evaluations at baseline (pre-operative), and at the 1st, 2nd, and 3rd months post-operatively using the following tools: Visual Appetite Scale Hoehn and Yahr Questionnaire Parkinson's Disease Quality of Life Questionnaire-8 Movement Disorder Society-Unified Parkinson's Disease Rating Scale - Part 2 Mediterranean Diet Adherence Scale Food Consumption Record Have their anthropometric measurements and body composition (e.g., weight, waist and neck circumference, upper arm circumference, handgrip strength) assessed.