Factors controlling the disposition of primary nutrients.

In the steady-state an organism maintains a dynamic balance between the dietary intake and metabolism of each of the primary nutrients, carbohydrate (CHO), fat and protein. However, such a steady-state, while generally true in adults in the long term, is never achieved during short periods (i.e. within 1 d) because of the discontinuous nature of food intake. The fact that we consume our food as meals, with postabsorptive periods in between, means that short-term storage in glycogen, adipose stores and tissue protein is necessary. Thus, the capacity to control the partition of nutrients after meals between immediate metabolism and storage, and then the mobilization of the stores during fasting, is essential for maintaining balance over the longer term.