Based on the experience of a friend who has worked with the morbidly obese & their family members (and my recollection of what I was told):
People who are modbidly obese (to the point where they can barely get out of their bed) have one or more caretakers who help them get basic tasks done. Usually relatives or boyfriend/girlfriend people.
People who are morbidly obese nearly always have emotional problems in addition to their physical problems. (Food in place of love is so common enough that it’s a movie stereotype.) My friend says these emotional problems are infectious, in that they spread to the caretakers.
For example, morbidly obese people do eat a lot more food than other people. But they often are in denial about this, and make claims that their body is overly-efficient at digesting food, etc. Seldom true; a careful record will show that they eat excessively. Frequently their caretakers are also in denial about the amount of food the obese person eats.
Note that usually a caretaker has to prepare & bring the food to such a morbidly obese person. If they would follow a sensible medical diet, and only bring the person that amount of food, the obese person would start to lose weight and improve their health. But these obese people are generally experts at playing on the sympathy of their caretakers, and getting them to bring more food. If there are multiple caretakers, they get real good at playing them off against each other. (Claiming that one caretaker is ‘starving’ them, and the other needs to make up for that.) These morbidly obese people are expert emotional manipulators of others (possibly necessary, when you can barely move from your bed).
She told me that to be successful, they usually had to treat the emotional problems, or the obesity just comes back. And this involves treating the emotional problems of the rest of family, too. This is seldom a problem of a lone individual. She said that often the rest of the family is close to obese also, just not as morbidly so as the one person. Very rare to have anyone thin as a caretaker in these situations!
She also indicated that this was usually a hard problem to solve, she didn’t have great success at it. Partly because it was usually quite serious, and quite ingrained by the time it became one of her cases. And because it usually involved so many people, many of whom didn’t participate willing in treatment. Often a real tough situation.