“i gotta say, when the shtf, out of shape people are not going to stand much of a chance of surviving.”
They will survive longer than the people who are ‘in shape’. Throughout history when there is famine, etc, the fat people live longer because their bodies use the fat. Skinny people die off.
Even 10 extra pounds can well mean the difference between life and death. Fat is, after all, simply stored energy.
Maybe in the abstract, under strictly controlled conditions, but in the real world, the fat tend to die faster. They're less healthy, less able to stand the real rigors of starvation situation. Prisoners on the Bataan Death March and in the camps later noted that the big men died first, and it was the scrawny little guys who tended to do best.
They can’t fight well. Won’t do well in riots or hiding, or running for cover. Huge targets. Not used to adrenaline and working their cardio system. And you will find dead fat people who have starved to death. Fat people still can only go 3 days without water, just like anyone else.