It would seem plausible that there may be more than one mechanism via which resource scarcity creates pressure for increased longevity (to increase the odds of offspring).
Also, I think studies of poverty show generally show that resource scarcity is almost always worse for health outcomes. Resource over-abundance is maybe also damaging but the idea that being resource scarce is beneficial for longevity because you need longer to mate seems almost certainly false to me.
Caloric restriction is probably exactly like exercise in that it was normal, so "scheduling" autophagy for the "famine" times meant it happened regularly and alongside similar systems.
What did it for me was that IF comes with muscle growth hormones increase.
I mean a 3-5 day hunt can look a lot like a marathon and a fast / IF mashed together.