Obesity, and... Obesity is the main health problem to qualify. Bmi (body mass index) >40, or >35 with associated health problems such as diabetes, sleep apnea, hypertension. Formerly had to be "morbidly obese" >100 pounds (45 kg) over ideal body weight. Bmi=wt (kg)/sqht (meters). Can be thrown off if very muscular. Measures weight not amount of fat.