I think that there is a lot more to morbid obesity than stopping eating. The body is very fragile when it is nutrient depleted. Ive watched a bunch of shows about the super crazy obese people and its not that theyre eating a ton of food, its that everything they eat is nutrient deficient. If they ate 10k calories a day thats not the worst thing in the world, but when all of it comes from pizza dough and chips what do you expect? When they start dieting, instead of getting lots of fat and calories that they are craving, they go on some super calorie/fat restricting diet. Instead of just eating good quality food in similar quantities, they starve themselves. Temporarily of course, because a person of that size has large nutrient demands.
At the same time, its not a disease. Its just not. They never learned to eat properly and they are paying for it. If someone never learned how to manage their finances, you wouldnt claim that their debt is a disease would you?