This prospective observational study investigates weight loss and metabolic changes in adults with obesity undergoing standard clinical diet-induced lifestyle treatment and counseling. Participants follow a very-low-calorie diet followed by a conventional weight loss diet in addition to lifestyle counseling and are followed for 12 months. The study examines weight loss as the primary outcome and characterizes changes in body composition, fat distribution, glucose metabolism, inflammation, and adipose tissue biology as secondary outcomes.