[The role of physical activity in obesity prevention].

Obesity is a chronic, multifactorial disease whose development is influenced by genetic, neuroendocrine, psychosocial and environmental factors as well as physical inactivity. Therefore, physical activity is a central pillar in the prevention and treatment of obesity. As well as increasing energy expenditure, it affects muscle mass, insulin sensitivity, fat metabolism, inflammatory processes, mental health, sleep and functional capacity. This narrative review summarises current guidelines, meta-analyses and representative monitoring data on the role of physical activity across the lifespan with regard to both prevention and treatment.In terms of prevention, general and age-specific physical activity recommendations for moderate and vigorous activity and the reduction of prolonged periods of sitting apply. In terms of treatment, weight loss achievable through exercise alone is usually moderate in adults. However, physical activity is independently associated with significant improvements in body composition, fitness, metabolic health, mobility and quality of life.From a public health perspective, promoting physical activity also requires environmental approaches, such as safe walking and biking paths, attractive and accessible spaces for physical activity, activity-friendly educational and work environments, and healthcare services that avoid stigmatization. Physical literacy-as a competency-based construct comprising motivation, self-confidence, physical competence, knowledge and understanding-can help to establish physical activity as a long-term resource for health and well-being, rather than merely as a means of preventing weight gain or losing weight.