fasting followed shortly thereafter by gluconeogenesis. In the adult,
gluconeogenesis converts approximately 75 grams of protein per day into amino
acids (especially alanine), which then moves to the liver for gluconeogenesis.
These early changes of starvation are accompanied by a decrease in insulin and
increase in glucagon production. The respiratory quotient (C02/O2) is low at
0.85 indicating oxidation of both carbohydrates and fats.
The late phase of starvation (greater than 4 days) is characterized by
adaptation of the brain to use ketone bodies from fat in place of glucose from
protein. Indicative of the decrease in protein catabolism and increase in fat
catabolism, the respiratory quotient decreases to 0.7 consistent with pure fat
oxidation. Gluconeogenesis persists in the kidney with resultant decreased
nitrogen in the urine to less than 5 grams per day.
Starvation in infants is a more precarious situation because of the minimal
stores of fat and protein, which are further compromised in prematurity. Vital
accretion of nutrients occurs during the last trimester of pregnancy. Decreased
enteral intake and high metabolic demand also increase problems for infants with
surgical, cardiac and chronic lung disease. The hazards of inappropriate
nutrition for infants include bone demineralization, rickets, cholestatic jaundice,
poor wound healing, impaired lung function and slow growth, which can affect
both short and long term outcomes.