References

Protein: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients)(2005) page 692 (Tolerable upper intake levels for protein):

20% of Swedish people following a LCHF diet (Eat Like a Swede Blog)

No carbs: "The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed."Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients)(2005) page 275:

Keto Calculator - Helps calculate how much of each macronutrient you need for a ketogenic diet