Obesity is a significant global health concern affecting adults and children, with three out of four adults and one in five children being overweight or obese. While Body Mass Index (BMI) is a common screening tool, understanding obesity involves a complex interplay of lifestyle, environment, and genetics. Factors like diet, physical activity, sleep, medications, and inherited genes contribute to weight gain, increasing risks for heart disease, diabetes, high blood pressure, breathing problems, and certain cancers. Societal influences such as neighborhood design and food access also play a role.