Just thought I'd add my twopence. I can't speak from an over or under eating perspective, but if we work from the standpoint of addiction then I can maybe shed some personal light.
A close family member died nearly a year ago after a lifetime of addictive behaviours. What began as a reliance on sleeping pills and uppers dissolved into the use of various over the counter medications to use as crutches.
Eventually alcohol replaced everything, and became an extra member of the family for over a decade. As my family member's illness progressed they became increasingly incapable of the activities of daily living (washing, dressing, feeding, socialising, mobilising, maintaining personal safety etc).
My family became irate with those who supported my family member to meet their needs "cut them off, they'll have to dry out and behave then" they said, but even with doctors advising that a fatal incident was as close as six months away my family member could not stop drinking.
When they became housebound and totally dependent on others for all their needs again my family said "cut them off, you're killing them by bringing the booze to them". But by this stage it was far too late to rectify the damage done, and those that continued to help my relative felt that the only way to provide any satisfaction and quality of life was to allow a (limited) but constant access to alcohol.
My relative is free of their enormous pain now, as are those of my family who chose to continue contact and to assist where they could.
My point (laboriously made) is that sometimes the only happiness in an addict's life is their addiction, and much though it will kill or maim them, sometimes it may be the only kindness a carer can provide. To my mind to reach a size that endangers your health and leaves you reliant on others for your daily needs must be a long road. To have your size and addiction recognised for what they are may be an even longer road, and to rectify the damage done may be insurmountable (COPD, diabetes, heart disease, gangrene, poor/no physical mobility, limb loss etc etc), so maybe there is a kindness once such a point has been reached to continue to support the needs of the addict?
I remember having read articles written by the family and friends of anorexics who have died, and they commonly speak of the anxiety leading up to death: that they should have "done more" to protect their loved one from dying so cruelly. But afterwards feeling only relief that their suffering was ended.
I don't know if I could control an addiction that I would have to feed a little every day in order to survive. And I don't know if I could do it with all the world judging me for my size and appearance.
All that said, there is a lot to be done in terms of food and diet education long before the point of morbidity and mortality. Much as with all addictions: there is a tipping point, and intervention before that point is usually very successful. Not that I have any idea what that intervention should be.