“Overweight” is defined as an excess amount of body weight, including fat, muscle, bone and water. By contrast, “obesity” specifically refers to an excess amount of body fat. Some people, such as bodybuilders or other athletes with a lot of muscle, can be overweight without being obese.
Overweight and Body Mass Index (BMI)
According to the Body Mass Index, a BMI of 25-29.99 signifies “overweight”, while a BMI of 30-39.99 signifies “obesity” and 40+ signifies morbid obesity.