> simple carbs are basically a slow acting poison to various internal organs and over time bring stuff like diabetes.

Do you have any evidence for this? The problem with simple carbs (if you don’t already have insulin issues) is that they’re easy to digest and provide minimal satiety so you end up consuming significant calories.

But as far as I’m aware there is no evidence that they’re worse for you than the rapid calorie addition.

These athletes are eating nutritionally complete diets overall. The simple carb intake is a strategy just for the run itself.

That said, pretty much everything about highest-end athletics is net negative for long-term health. It’s incredibly hard on the body to run a marathon in general, let alone at record breaking pace.

I don’t think there is any elite level sport that doesn’t trade long term health for performance in competitions.