A german website gave this synopsis of the following studies:

Sources of literature:
1. Dr. med. Wolfgang Lutz: Life without bread. The scientific bases of low carbohydrate nutrition.
INFORMED, specialized agency for medicine GmbH, Graefeling, 1998

2. Klaus Arndt & Stefan Korte: The ANABOLIC DIET , Ketogenic nutrition for the Bodybuilder, Novagenics publishing house 1997

The probability that people will react with an intensified fat dismantling to the ketogenic diet lies with approximately 75 per cent of all people. /1 /,/2/
This statement is based on the fact that humans in the course of the evolutionary development changed themselves from the hunter and gatherer to field farmer and thus carbohydrate-eater. Only during approximately the last 10,000 years has the adjustment of the organism been made to carbohydrate consumption, what corresponds to approx. 500 generations. Some humans have made the adaptation to carbohydrates already respectively:

25% group
Today one assumes about 25 per cent of humans are carbohydrate-adapted. They have hardly any problems with carbohydrate consumption. It causes neither an increased insulin payment, nor Hyperinsulinaemia, and the risk for predominance of heart cycle diseases lies accordingly low.
These lucky ones can eat large quantities without increasing risk.

50% group
Between these two extremes lies the group which reacts differently and strongly to carbohydrates. That would be thus 50 per cent of all people. Supplied carbohydrates are not optimally converted. Into this group fall all those, which exhibit an annoying symptom in the belly region. With a conventional diet it is difficult not to get persistent belly fat, since these persons react with an intensified insulin payment to carbohydrates. If you fall in this group, the ketogenic Diet is exactly the correct solution of the problem.

25% group
The portion of humans, who are not adapted to carbohydrate consumption, is likewise with approximately 25 per cent. Therefore they react with higher insulin output, the risk for the development of Hyperinsulinaemia lies very highly. The higher insulin output explains also, why these persons with normal calorie quantities have a fast increase in weight. A calorie-reduced, charbohydrate-rich diet helps here only little. For these persons the ketogenic diet is optimal.