Well they don’t intentionally do it on purpose. You will find a history of sexual & physical abuse behind a morbidly obese person. Food began as a comfort to emotional pain but in time it becomes simply an addiction.
So sad. When I was younger, I thought what the heck is wrong with fat people, and why don't they get themselves out of it? Then when I got older I put on a few pounds, and understood how hard it is to resist the temptation of eating. But most of us know not to let the overeating get out of control. As you said, food is a comfort to emotional pain for morbidly obese people. They languish in emotional hurt and binge on food to comfort themselves. That show I watched a few days ago showed the emotional hurt these people have. The doctor referred the woman to a psychologist to help the woman get to the roots of her emotional hangups and get over it, because the doctor said without emotional healing the woman would just get obese again despite the surgery and dieting help. In this woman's case, it was neglect by her parents paying all their attention to a sibling (with physical ailments). She got over the hurt, and began eating healthy food and exercising.