I accept that to a degree, and certainly where medical, genetic and other factors beyond the control of the individual come into play, I completely understand it.
That said, a LOT of obesity is due to a simple lack of discipline. I am a foodie; I love to eat, but as my work has made me a lot more sedentary than I used to be, I've cut my intake substantially, and have become far more attentive to what I'm eating.
I say that with no intention whatsoever of elevating myself above others, but to the contrary, to say I'm nothing special and if I can do it, pretty much anybody can if they simply exercise the discipline to do so.
Discipline is a virtue, but discipline applied to the wrong kind of problem can be harmful and an expression of stubbornness and even fanaticism. And most health issues are a complex mix of genetics, luck, and personal choices. The essential role for disciple may then be to go to the doctor, follow instructions, and take you medicine. For the aged and ill, a crash diet and an exercise binge to address obesity can be hard to apply and problematic in results. The best results come from providing competent, individualized medical advice and care.