This clinical trial aims to determinate whether a structured exercise program, supported by telerehabilitation, can help individuals with severe obesity who are going to undergo bariatric surgery. The main objective of this study is whether a structured exercise program, including both supervised and home-based workouts, leads to greater body fat loss and improved strength compared to usual care. Furthermore, it also aims to evaluate other potentially affected aspects, such as body composition and functionality, quality of life, cardiovascular fitness, and various genetic and metabolic factors. This study is a randomized clinical trial with two groups: * The intervention group will follow a structured exercise program both pre- and post- surgery. * The control group will receive standard care, including nutritional counseling and general health advice. The study will include 72 adults with severe obesity (36 men and 36 women), all of whom will be randomly assigned to either the intervention or control group. Participants in the exercise group will follow these steps: 1. Before Surgery (Prehabilitation): A 26-week program with aerobic and strength exercises, done in-person or remotely 2-4 times per week. 2. Pre-Surgery Maintenance: A flexible period before surgery where participants continue exercising on their own. 3. After Surgery (Rehabilitation): A 20-week program focused on recovery and strength. 4. Post-Surgery Maintenance: A long-term, self-guided phase to maintain progress. Participants in the exercise group will also receive the same care as the control group, including nutrition counseling and medical checkups. To evaluate participant progress, a series of measurements will be carried out, including: * BMI and body composition * Physical function assessed through isometric strength tests and other measures such as the Sit-to-Stand test and the 6-Minute Walk Test * Quality of life and lifestyle assessed using validated questionnaires * Daily physical activity measured with pedometers * Metabolic and genetic analysis from blood samples If proven effective, this program could help establish structured exercise with telerehabilitation as a standard component of obesity care. The results may support the integration of exercise programs into clinical practice, leading to improved long-term outcomes for individuals with severe obesity undergoing bariatric surgery. Additionally, insights into genetic and metabolic factors may contribute to the development of personalized treatment strategies.