I agree that people do need to take responsibility for their health, and this obviously includes their weight.
However, I think that there probably are clinical conditions (such as depression) and psychological conditions (such as low self esteem) that will affect an individual's ability to take responsibility for their own health/weight and which conditions might well prevent them, in ways we do not understand yet, from taking that responsibility.
I also think that more research needs to be done into the effects certain foods have on insulin levels, which effects in turn affect how the brain, the nervous system, and muscles get on with their job.
So yes, people need to be responsible for themselves, but sometimes they can't do it.
That said, I'm baffled as to why a man as young as twenty didn't go for help with his problems before he got to such a state, which cannot be good for his mental or physical health.