Imagine your body is a home with a fireplace in the middle and the heat required to keep it at a comfortable\livable temp is keeping the fireplace burning at a manageable and constant pace. To do this you have two fuel-types at your disposal: Kerosene and Charcoal. (in this analogy Kerosene is carbohydrates and coal is fat). American diets are high in carbs, which is like throwing a bucket full of kerosene on that fire. Will it keep the house warm? Sure, but it burns down fast so you have to keep throwing bucket after bucket on it to keep it going, consuming tons of kerosene, and you get these huge spikes in heat. It is much harder to control the strength of the flame, and thus much harder to keep the house at a constant, comfortable temp.
A ketogenic diet helps control blood sugar levels. It is excellent for managing type 2 diabetes, sometimes even leading to complete reversal of the disease. This has been proven in studies. It makes perfect sense since keto lowers blood-sugar levels, reduces the need of medications and reduces the potentially negative impact of high insulin levels.