Metabolic States of the Body: The Absorptive State

The absorptive state is a well-fed period lasting approximately four hours after a meal when the body absorbs nutrients from the gastrointestinal tract.

The carbohydrates, proteins, and lipids consumed are broken down into monosaccharides, amino acids, free fatty acids, and monoglycerides for absorption.

These absorbed nutrients are used for immediate body requirements or stored for later use.

In the liver, absorbed monosaccharides are converted to glucose for energy production or stored as glycogen.

Surplus glucose is also converted to fat as very low-density lipoproteins, or VLDLs, for accumulation in adipose tissue.

Adipose tissue stores triglycerides delivered by VLDLs, with a small fraction of lipids used for energy production.

Some amino acids are deaminated in the liver to produce keto acids for ATP production or to synthesize glucose and fatty acids.

A post-meal rise in blood glucose and amino acids increases insulin production by the pancreas.

Insulin stabilizes blood glucose levels by promoting cellular glucose uptake and glycogen synthesis while inhibiting glycogen breakdown and gluconeogenesis.