Exercise is an essential pillar for the health of all individuals, as it contributes to physical, mental, and emotional well-being. Various international organizations, such as the World Health Organization, advocate for the integration of exercise into healthy lifestyles, recognizing its im-portance in disease prevention and improving quality of life. However, despite the general consensus on its value, there is no universal agreement on specific prescriptions for vulnerable groups, highlighting the need for personalized approaches that consider the unique characteristics and needs of each individual. It has been proposed that a moderate aerobic exercise training program could promote positive outcomes in individuals living with overweight and obesity, particularly with an emphasis on reducing injury risk, ensuring high adherence, and achieving favorable health changes. In this regard, the present protocol establishes the basis for a randomized clinical trial based on exercise prescription at the maximal fat oxidation rate in young individuals with overweight and obesity, with a duration of 16 weeks. Throughout the study, biochemical changes (cholesterol, glucose, triglycerides, and inflammatory markers), metabolic changes (de-termination of fat and carbohydrate utilization rates during rest and exercise), and epigenetic changes (focusing on microRNAs associated with adipogenesis, inflammation, and fat metabolism) will be monitored.

Obesity is a public health problem that affects millions of people in Mexico and around the world. This disease has not only increased alarmingly in recent decades but has also been recognized as one of the main risk factors for chronic diseases such as dia-betes, cardiovascular disease, and certain types of cancer. By 2022, it was estimated that 890 million adults were living with obesity and the trend continues to in-crease with obesity occurring at younger and younger ages.

The critical levels of this disease urgently demand the need to address this crisis on multiple fronts. Traditional strategies to combat obesity have focused primarily on individual responsibility, emphasizing the need to improve diet and increase physical activity. However, reducing obesity to a mere problem of willpower is insufficient to under-stand the complexity of the problem, which involves genetic, psychological, social, eco-nomic, environmental and, above all, individual factors, where dietary and exercise pre-scription is fundamental for its efficacy and adherence by those affected.

In this sense, it is crucial to conduct studies that explore the effectiveness of training and physical activity programs specifically designed for people with obesity. These pro-grams should not only focus on improving biological markers of health, such as body fat reduction, lipid profile improvement, maintenance of lean mass or exercise-associated injury limitations, but also on promoting long-term adherence and the creation of healthy habits. Understanding how to adapt exercise to the specific needs of this population is essential to develop more effective and sustainable interventions.

If these issues are not specifically addressed, the consequences will be serious. The prevalence of obesity will continue to rise, increasing the number of people at risk of de-veloping chronic diseases, reducing their life expectancy and quality of life. In addition, the health care system will face increased costs and pressure, which will make this silent pandemic even more difficult to manage. Thus, the present protocol aims to evaluate the effect of a personalized physical training program at maximum fat oxidation (FatMax) for 16 weeks on biochemical, metabolic and epigenetic parameters in overweight and obese young adults.

The subjects assigned to each group will participate in a randomized clinical trial, with a duration of 16 weeks of intervention. Measurements of all variables will be taken on the first day of the evaluation (considered the basal state) and at the end of 16 weeks of the intervention according to the group in which they were randomized, to be followed by sta-tistical analysis of the data. The variables contemplated involve assessments of body composition and physical capacities, biochemical variables, epigenetic variables and alternate variables.

Inclusion Criteria:

• Both genders
• Daily energy expenditure <4 METs
• Body mass index ≥25 kg/m2
• Acceptance of informed consent

Exclusion/elimination Criteria:

• ≥100 ml of alcohol consumption per week
• Consume a dietary supplement or pharmacological treatment
• Have limitations to perform regular physical activity
• Have a chronic non-communicable disease
• Answer "yes" to any of the questions on the Physical Activity Readiness- Questionnaire for Everyone (PAR-Q+); which represents a health risk.
• <80% attendance at exercise sessions

Publication of manuscripts without any name of a participant

Statistical Analysis will be conducted without knowledge of gropus allocation.