Question

during periods of fasting, why is fat said to have a protein - sparing effect?
multiple choice
the body must have an adequate fat intake in order to absorb and metabolize proteins.
the body does not oxidize its proteins unless it has consumed its fat reserves first.
the body must have an adequate protein intake in order to absorb and metabolize fats.
the body metabolizes fats and proteins through the same metabolic pathways.
the body oxidizes its spare protein before it depletes its fat reserves.

Explanation:

During fasting, the body first uses carbohydrates (if available), then fats for energy. Proteins are a last - resort energy source as they have crucial structural and functional roles (e.g., enzymes, muscle tissue). Fat being used as an energy source before proteins means proteins are "spared" from being oxidized for energy.

• The first option is incorrect because fat intake is not directly related to protein absorption/metabolism in this context.
• The third option is wrong as protein intake is not about fat absorption/metabolism in terms of the protein - sparing effect.
• The fourth option is incorrect. Fats and proteins have different major metabolic pathways (e.g., beta - oxidation for fats, deamination for proteins).
• The fifth option is the opposite of what happens (fats are used before proteins).

Answer:

The body does not oxidize its proteins unless it has consumed its fat reserves first.