Fasting state, continued metabolism

In studies of animals it hccomcs technically difficult to make observations under standard conditions which include rest. Restraining an animal increases the metabolic rate and inactivation through anesthesia lowers ii ruminants and other plani eaters cannot he brought into a fasting state unless they are deprived of food for prolonged periods of time small animals (c.g., shrews) have such high metabolic rates that they must cat almost continuously lo sustain a normal metabolic rale, clc. 

Di Abietes has a ketoacidosis. When the amount of insulin she injects is inadequate, she remains in a condition similar to a fasting state even though she ingests food (see Chapters 2 and 3). Her liver continues to metabolize fatty acids to the ketone bodies acetoacetic acid and p-hydroxy-butyric acid. These compounds are weak acids that dissociate to produce anions (ace-toacetate and p-hydroxybutyrate, respectively) and hydrogen ions, thereby lowering her blood and cellular pH below the normal range. 

By contrast, if the intake of metabolic fuels is greater than is required to meet energy expenditure, the body will spend more time in the fed state than the fasting state there will be more accumulation of nutrient reserves than utilization. The result of this is an increase in body size, and especially an increase in adipose tissue stores. If continued for long enough, this will result in overweight or obesity, with potentially serious health consequences — see Chapter 6. 

An adult has a requirement for a dietary intake of protein because there is continual oxidation of amino acids as a source of metabolic fuel and for gluconeogenesis in the fasting state. In the fed state, amino acids in excess of immediate requirements for protein synthesis are oxidized. Overall, for an adult in nitrogen balance, the total amount of amino acids being metabolized will be equal to the total intake of amino acids in dietary proteins. 

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