ADAPTATION DURING STARVATION

ADAPTATION DURING STARVATION

Protein:

• After an overnight fast, amino acids provide glucose by gluconeogenesis.

• Gluconeogenesis from amino acids increases during the first three days of starvation.

• Then, it declines as the body adjusts its metabolism to use ketone bodies as a primary fuel source.

Fatty acids

 • As starvation continues, gluconeogenesis from amino acids declines because free fatty acids mobilized under the condition of low insulin levels are oxidized preferentially.

 • The mobilization of free fatty acids is unchecked and lasts as long as the reserves of triacylglycerol allow.

Ketone bodies:

• The high level of acetyl CoA in the liver drives the formation of ketone bodies produced at the maximum rate as early as the third day of starvation.

 • When the plasma level of ketone bodies is high enough, the cardiac and skeletal muscles and brains are readily utilized.