Metabolism in Fed and Fast States

What does the body primarily utilize for energy during the fed state?

During the fasting state, what happens to insulin levels in the blood?

Which process is inhibited during the fed state due to high insulin levels?

Which process is stimulated in the fasting state to increase blood glucose levels?

Which organ synthesizes ketone bodies as the major fuel source during starvation?

What is the major fuel source during a long-term fast or starvation?

What is used for the synthesis of new proteins during the fed state?

What is primarily stimulated by high insulin levels during the fed state?

What happens to the breakdown of fatty acids and triacylglycerols during the fed state?

What adapts to utilize ketone bodies as fuel during starvation?

Energy Utilization in Different States

The body primarily uses glucose for energy during the fed state due to the availability of nutrients from food intake.
During the fasting state, insulin levels in the blood decrease as the body shifts to energy conservation after the lack of food intake.

Hormonal Regulation and Metabolic Processes

In the fed state, insulin inhibits gluconeogenesis, the process of generating glucose from non-carbohydrate sources, due to elevated insulin levels.
In the fasting state, glycogenolysis is stimulated to increase blood glucose levels by breaking down glycogen stored in the liver.

Key Organs and Fuel Sources

The liver synthesizes ketone bodies which serve as a major fuel source during prolonged starvation.
During long-term fasting or starvation, fatty acids become the primary fuel source for body tissues, providing energy through beta-oxidation.

Protein Synthesis and Insulin Effects

Amino acids from dietary protein are utilized for the synthesis of new proteins during the fed state, supporting growth and repair.
High insulin levels during the fed state primarily stimulate anabolic processes, including glycogen synthesis and lipogenesis (fat storage).

Lipid Metabolism and Adaptation

In the fed state, the breakdown of fatty acids and triacylglycerols is suppressed, preserving energy storage for future use.
The brain and other tissues adapt to utilize ketone bodies as alternative fuel during starvation, enabling survival despite glucose scarcity.

Learn about how the body regulates energy fuels in response to food intake and fasting. Understand the metabolic processes in the fed state, including the role of insulin and utilization of nutrients for energy.