During starvation, which energy source becomes predominant?

During starvation, which energy source becomes predominant?

• A. Carbohydrates
• B. Protein
• C. Fat
• D. Alcohol

Answer: (C)

During starvation the body shifts to using fat stores as the main energy source, preserving protein. When dietary carbs run out and glycogen is depleted, insulin falls and hormones stimulate lipolysis. Triglycerides in adipose tissue are broken down into fatty acids and glycerol; fatty acids are released into the blood and oxidized by most tissues to meet most energy needs. This fat-derived energy also helps spare muscle protein from rapid breakdown. Glycerol feeds gluconeogenesis to maintain blood glucose, and as fasting continues, the liver converts fatty acids into ketone bodies, which become a significant fuel for many tissues, including the brain. So fat is the predominant energy source during starvation.

During starvation the body shifts to using fat stores as the main energy source, preserving protein. When dietary carbs run out and glycogen is depleted, insulin falls and hormones stimulate lipolysis. Triglycerides in adipose tissue are broken down into fatty acids and glycerol; fatty acids are released into the blood and oxidized by most tissues to meet most energy needs. This fat-derived energy also helps spare muscle protein from rapid breakdown. Glycerol feeds gluconeogenesis to maintain blood glucose, and as fasting continues, the liver converts fatty acids into ketone bodies, which become a significant fuel for many tissues, including the brain. So fat is the predominant energy source during starvation.