Over 370 million children and adolescents in the world are obese. Obesity is a disease that can affect both physical and mental health. Learn what can be done to prevent and treat obesity and promote healthy lifestyles. Level 3 readers are aimed at children who are reading by themselves and can grasp new concepts. Key words and captions help readers understand new vocabulary and more challenging sentence structure. ¿This project has been made possible in part by the Government of Canada.