My problem with the "Let them die" approach is that they do care about themselves and want to lose weight. Every single obese person in the world wants to lose weight (except for those with psychological disorders). Much like quitting a drug (i.e. smoking), efforts to lose weight are typically unsustainable and short-lived. Why?
Because obesity is a disease. Most people who become obese actually have very little excuse...the often cited "slow metabolism" is incredibly rare, and indeed, the #1 reason people get obese is overeating. That's inexcusable and something that needs to be addressed by society. But that's not the topic of this discussion.
Once you are obese, you do need help. Obesity is co-morbid with other issues at rates of virtually 100%: insulin resistance and leptin resistance. Obesity is often due to a dysfunctional hunger system; that is, the people eat to satisfy the mesolimbic reward system rather than physiological hunger.
So let's say you try to lose weight. With all your leptin resistance, it's tough for you to "feel full." Now start taking bodyfat out of the equation as you drop a few pounds. You now have leptin resistance (demonstrated to be almost irreversible) coupled with less leptin release. To make matters worse, you start hyper-secreting ghrelin (largely irreversible), with amplitudes hundreds of percent greater than normal people. Your body essentially thinks you are starving physiologically, and you perceive it as such. So now you take a pre-existent dysfunctional reward system (pleasure eating) and add in extremely powerful physiological hunger signaling, and suddenly you realize that it's not so easy to just "put down the fork." When you are this hungry, you can't think about anything else. You need to eat and end this starvation.
But people have lives! They have jobs, responsibilities, etc. We're not all on "The Biggest Loser" where we can just say "Screw it, I'm just gonna focus on absolutely nothing but weight loss for the next _________ months." Obesity is often seen in poorer neighborhoods, where such an attention to weight loss is definitely out of the question...and access to filling food is minimal.
Cliffs:
-Obesity has several physiological, not psychological, factors that "lock you in" for life. The most significant of which is neuroendocrine signaling.
-Gastric bypass surgeries have an exceptional track record for obesity recovery not because they reduce stomach size, but because they resection almost the entire ghrelin-secreting part of the stomach, reducing perceived hunger.