Some people DO keep it off. Ive never been obese but ive been overweight, extremely unhealthy, pre diabetic, couch-potato for years at a time. For me, it's always a matter of getting into the mindset that these things are not just "not good," they are literally poison for me!

I've seen a few obese friends of mine lose weight and gain it back. And while I can't put words in their mouths, I have never noticed them have the attitude that "being obese will kill me."