Obesity becomes "morbid" when it reaches the point of significantly increasing the risk of one or more obesity-related health conditions or serious diseases (also known as co-morbidities) that result either in significant physical disability or even death. As you read about morbid obesity you may also see the term "clinically severe obesity" used. Both are descriptions of the same condition and can be used interchangeably. Morbid obesity is typically defined as being 100 lbs. or more over ideal body weight or having a Body Mass Index - BMI of 40 or higher. According to the National Institutes of Health Consensus Report, morbid obesity is a serious disease and must be treated as such. It is a chronic disease, meaning that its symptoms build slowly over an extended period of time. Use our Body Mass Index - BMI Calculator to determine your Body Mass Index - BMI.