The prevention of overweight and obesity in children and adolescents focuses on education and the promotion of healthy lifestyles. The World Health Organization indicates that the level of obesity-related diseases has increased almost threefold since 1975, now affecting all socioeconomic groups regardless of age or ethnicity. Particularly alarming is the increase in obesity among children and adolescents. Projections indicate that by 2025 the disease could affect up to 268 million young people aged 5–17. The causes of the problem are complex, involving genetic and environmental factors, psychological factors, as well as inappropriate eating behaviors and insufficient levels of physical activity. In Poland, the lack of precise epidemiological data and systematic control of the problem of obesity among children and adolescents is a major challenge. It is important to take effective preventive measures, including nutrition education and the promotion of physical activity to change habits and prevent obesity. Projects such as “Colorfully means healthy”, “6–10–14 for Health”, and “Healthy Me” indicate the need for a multifaceted approach to the problem, involving government institutions, schools, families and non-governmental organizations. A successful fight against obesity requires long-term strategies, comprehensive educational and health activities that will promote healthy choices and change social attitudes toward nutrition and physical activity. Implementing these strategies is key to improving the quality of life and health of children and adolescents, as well as to reducing the long-term health and social consequences associated with obesity.