The word "Morbid" is used in a medical context. It indicates that your degree of overweight (80 pounds for females, 100 pounds for males) is commonly associated with other weight-related (co-morbid) life-threatening illnesses, e.g., diabetes, hypertension, degenerative arthritis, etc.

Obesity occurs when you eat more food than is required to take care of your body's energy needs. The excess food is stored as fat. There are several other factors that play a role in obesity:

Heredity

People vary in how efficiently their bodies' store fat. The ease with which foods are converted into fat and stored in the body is an inherited trait. While hereditary traits alone do not normally make a person obese, they can be extremely important factors in the overall picture.

Lack of Exercise

People who have poor exercise and activity patterns are much more prone to suffer from obesity. Daily exercise helps build muscle, uses stored calories and helps control excessive appetite by increasing feelings of well-being.

Improper Eating Habits

Obese people, particularly those whose close relatives are obese, almost always have improper eating habits in addition to a genetic predisposition towards obesity. Diets that are high in fat, are improperly balanced or too generous, contribute greatly to the cause of obesity. Dietary habits are learned habits. Part of the cure for obesity is changing poor dietary habits.

Emotions

Feelings of inadequacy, worthlessness and stress often cause people to turn to food for comfort. Obesity, particularly morbid obesity, can cause and aggravate those feelings. Rejection, occupational discrimination, and embarrassment about personal appearance increase the level of these feelings, even more. A vicious cycle is formed. Overeating to find comfort from emotions causes obesity. Uncomfortable emotions are increased by obesity, thereby, resulting in an increased tendency to over-eat.