Wow.
There was actually a study of US Soliders that lived through the equivalent (or worse, in some cases) of the Shoa -— the Battan Death March and related acts by the Japanese.
They lived (and live) to be quite old compared to their peers.
The issue though is it’s impossible to “correct” for people who are just so tough (or whatever) they live through such dramatic events and calorie reduction.
These same family members were just tough people, and you have a correlation vs. causation issue.