It has been estimated that the risk of cancer is about 6% lower in people who maintain a healthy body weight (body mass index [BMI] between 18.5 and 25 kg/m2) compared with those who are obese (BMI above 30 kg/m2). Lifestyle factors, such as a healthy diet, normal body weight, and physical activity, tend to be present together in the same people, and it is difficult to separate their independent effects. The greatest health benefit is achieved by having a healthy lifestyle (More information on Diet, Physical activity and Alcohol).