Which of the following statements is NOT true about obesity?

a) Obesity is defined as having a body mass index (BMI) of 30 or higher.

b) Obesity is a leading cause of preventable diseases such as heart disease and diabetes.
c) Obesity is only caused by overeating and lack of physical activity.
d) Obesity can increase the risk of certain types of cancer.
c) Obesity is only caused by overeating and lack of physical activity.