La cétose : quel niveau de glucides ?

Globalement, nous sommes dans le cadre d’un programme à 900 calories à environ 50-55 grammes de glucides par jour…ce qui correspond aux niveaux admis par la communauté scientifique notamment le SCOOP Report qui s’est positionné sur 55g après de longues tergiversations* pour qu’une cétose se passe bien.

De même l’article de Leonard J. Hoffer se positionne sur 100g pour indiquer ensuite qu’à 40g d’apports exogènes, on est « couvert ».

Au niveau pratique, il semble que la sensibilité à la cétose soit très variable selon les individus et que par mesure de précaution et pour que 100% de la population y soit, on devrait être à 40g...le type de glucides et le rythme d’absorption ne sont pas non plus abordés et ces 2 éléments viennent grandement influencer les résultats…rien de très clair donc…

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* There was an extensive discussion on the level of carbohydrates to be set for such foods in the Codex standard. It was proposed to reduce it to 40 g. However, the Committee on Nutrition and Foods for Special Dietary Uses had finally agreed to retain the level of 50 g and to refer to 'available' carbohydrates.

There has been a long-standing controversy about whether diets high or low in carbohydrate are superior in sparing protein in obese individuals undergoing hypocaloric dieting. The proposed minimum carbohydrate levels ranged from 30 g up to 100 g per day in VLCDs providing from 450 kilocalories to 800 kilocalories per day (CX/NFSDU 95/3, -Add.1, -Add. 2).

Some scientists have favoured the ketogenic (low-carbohydrate) diets on the basis that ketone bodies spare protein during caloric deprivation (see Section 6.1.). Others have found little or no difference between ketogenic and non-ketogenic diets.

Yet, other scientists favour the non-ketogenic diets since they have observed that isocaloric replacement of fat by carbohydrate is associated with an improved N-balance. Optimum inhibition of endogenous protein degradation and ketogenesis is only attained at a daily carbohydrate intake of 100 g per day. Endogenous gluconeogenesis in fasting individuals ranges between 2 and 2.9 g per kg body weight and day. Hence, a compensation of endogenous gluconeogenesis from amino acids and thus a conservation of endogenous protein stores cannot be achieved through minor quantities of alimentary glucose (Elia, 1991; Vazquez and Adibi, 1992).

On the other hand a negative energy balance will lead to a certain endogenous protein degradation taken the composition of the body weight into consideration (ratio of 75/25 FM/FMM).

Therefore both the direct protein sparing effect of addition of carbohydrate as well as the non-ketogenic property of higher levels of carbohydrate should be taken into consideration. The members of the SCOOP working group favoured the desirable level for carbohydrate to be 55 g of 'available' carbohydrates.