Obesity is a medical condition where excess body fat has accumulated to the extent that it may have a negative effect on health, including heart disease, diabetes and certain cancers.

It is often measured using Body Mass Index (BMI), which uses a person's height and weight to estimate body fat. Obesity is typically defined by a BMI of 30 or higher. However, waist circumference and body composition are also important.

More than just a number — obesity is influenced by genetics, lifestyle, environment, and societal factors.