[theorique]

There's no dietary or metabolic need for carbohydrate. The human body can survive and thrive perfectly well with only fat and protein as macronutrients. Practically speaking, doing that is challenging and complicated because most foods are a mix of all three macronutrients.

[Kayou]

But do you need sugar? Or you don't need either sugar nor carbs? It seems strange to me. EDIT: it seems that if you use only your fat, you'll end up producing too much Ketones which leads to Ketoacidosis. Doesn't sound good.

[mizzack]

No, ketosis doesn't lead to ketoacidosis unless you completely neglect to manage your insulin.

[nugi]

Ketosis is perfectly healthy. You are very confused.