Explanation:

When the body temperature is high, doctors usually advise the consumption of light food. This is because at high temperatures, certain enzymes in the body can get denatured and cannot function well. Let's understand this in detail:

1. Enzymes and their role:
Enzymes are proteins that act as catalysts in various biochemical reactions in the body. They play a crucial role in facilitating the breakdown of complex molecules into simpler ones, which are then utilized for various metabolic processes. Each enzyme is specific to a particular reaction and speeds up the rate of that reaction.

2. Temperature and enzyme activity:
Enzymes have an optimal temperature range at which they function most efficiently. This range is usually around normal body temperature, which is approximately 37°C (98.6°F). When the body temperature rises significantly above this optimal range, the activity of certain enzymes can be affected.

3. Denaturation of enzymes:
Denaturation refers to the structural changes in proteins, including enzymes, leading to loss of their normal shape and function. High temperatures can cause the denaturation of enzymes by disrupting the weak bonds that maintain their specific three-dimensional structure.

4. Effect of denatured enzymes:
When enzymes become denatured, their active sites, which are responsible for binding to the substrate and catalyzing the reaction, may no longer be functional. This can lead to a decrease or complete loss of enzyme activity. As a result, the biochemical reactions that depend on these enzymes may not occur efficiently or may not occur at all.

5. Importance of light food:
Consuming light food when the body temperature is high is advised because light food is generally easier to digest. Heavy, fatty, or complex meals require more enzymatic activity for digestion, which can be compromised when the body temperature is high and enzymes are denatured. Light food, on the other hand, is less demanding on the digestive system and can be more easily processed even with reduced enzyme activity.

In conclusion:
Consumption of light food is advised when the body temperature is high because at high temperatures, certain enzymes can get denatured and lose their functionality. This can affect the efficiency of biochemical reactions in the body. By consuming light food, the digestive system is not burdened, and the body can still obtain necessary nutrients even with compromised enzyme activity.