Ketogenic diets - when they're not ketogenic.

High in the Arctic, Eskimo!

It's generally assumed that eating less than 50g/day of carbohydrate results in ketosis. Assume makes an ass out of "u" and "me". From Lyle McDonald's book The Ketogenic Diet:-

The Ketogenic Ratio (KR) = K/AK, where K = Ketogenic stuff and AK = Anti-ketogenic stuff.

K/AK =  (0.9*Fat + 0.46*Protein)/(1.0*Carbohydrate + 0.1*Fat + 0.58*Protein) where Fat, Protein & Carbohydrate are in grams.

For the treatment of epilepsy (very strongly ketogenic), K/AK must be greater than 1.5. For people who want to get into benign dietary ketosis, K/AK can be lower.

Eskimos eat a diet containing virtually zero dietary carbohydrate (~50g/day as muscle & liver glycogen). However, they are not in ketosis. See STUDIES ON THE METABOLISM OF ESKIMOS.

Eskimos eat so much protein that the Anti-ketogenic effect of Protein offsets the Ketogenic effect of Fat + Protein. Table IV is interesting, as it shows how much energy is lost as ketones on the third day of successive fasts in non-Eskimos (Subject #1 fasted once only). Note:- Beta-hydroxybutyric acid  produces 5kcals/g.

Subject #1:- 10.5kcals. ?kcals, ?kcals.
Subject #2:- 100.5kcals, 7.0kcals, 2.75kcals.
Subject #3:-  9.75kcals, 0.0kcals, 0.0kcals.

The answer is "not a lot" (except for Subject #2 on the first fast).