TL;DR: there are 2 monkey studies, with unclear/conflicting results, both had pretty shitty diets, the calorie restrictions were severe, the benefits minimal at best.
The quote I provided was from the article. I’ve read the whole thing and I’m still parsing it (and your statement about both being fed shitty diets) as going against your original assertion: “Studies of caloric restriction in monkeys didn’t cause lifespan extension, casting doubt on its effect in humans.”
According to Attia, the studies weren’t specifically studying life extension, and all the diets were non-typical for the monkeys being studied. So, to me, this argues not that caloric restriction doesn’t cause lifespan extension in monkeys, but that we cannot know from these studies whether caloric restriction with a healthy diet causes lifespan extension in monkeys, which is what we really want to know. I wouldn’t expect to extend lifespan by eating hamburgers and fries but less of them, and that seems analogous to what the studies did.
To me, this simply leaves the question of caloric restriction in humans unanswered instead of casting doubt on it. Big difference.
TL;DR: there are 2 monkey studies, with unclear/conflicting results, both had pretty shitty diets, the calorie restrictions were severe, the benefits minimal at best.