Why would one expect a person who can't keep up with the simple instruction "eat less" to keep up with the complex instructions "get surgery, install this tube,

Why would one expect a person who can't keep up with the simple instruction "eat less" to keep up with the complex instructions "get surgery, install this tube, keep it sterile, empty it out into the toilet after every meal, get regular checkups...oh AND don't eat more to make up for the hunger you feel when you empty out your stomach."