Abstract
Purpose: To overview the physiological and health implications of carbohydrate deprivation as in the so‐called ‘Stone Age diet’ being used for allergy avoidance and weight loss.
Design: To consider the types of diet that place humans at or beyond the borderline of ketosis and to define the conditions that trigger the strongly ketotic state in non‐diabetic subjects. To consider the health consequences of ketotic acidosis and the wider health impact of diets made up principally of protein and fat.
Conclusions: Carbohydrate depletion occurs in starvation or at times when only protein and fat are being eaten. The resulting ketosis is due to the body's inability to carry out net synthesis of new carbohydrate from ketogenic metabolites. The resulting ketosis leads to acidosis, which may induce respiratory and oxygenation effects and negative effects upon renal function, bone mineral, calcium and nitrogen balance and upon the nervous system. The body's ability to form limited carbohydrate from either protein or glycerol should serve to provide those essential tissue and cellular structures which have a carbohydrate basis. Evidence of a need for dietary carbohydrate is provided by the increased incidence of some human chronic diseases associated with markedly elevated long‐term intakes of either protein or fat. Carbohydrate then appears to become essential by default, due to the need to provide adequate calories while maintaining protein and fat at adequate but not excessive levels. This conclusion may be significant, especially in the longer term, to those suffering from multiple allergies who react adversely to most carbohydrate foods and to long‐term dieters. Intermediate states that just avoid ketosis may still be of benefit to allergy sufferers, while slimmers using this kind of diet need to reach a ketotic state in order to succeed.