[api]

Too much carbohydrate creates issues, but I think the real culprit is sugar. The science is pretty solid there. Refined sugar can border on toxic.

Close behind sugar would be heavily processed carbohydrates like white bleached flour, etc., which are not that much better.

But there are of course confounding factors. There are people who eat more of this stuff and are healthy, but they seem to get a lot of exercise. That probably helps in multiple ways including burning up extra sugar quickly.

I'd hypothesize that high carb and especially high sugar diets are really unhealthy when coupled with a more sedentary lifestyle.