Which macronutrient provides quick energy but lasts for a short time?

Carbohydrates are the macronutrient that provides quick energy but lasts for a short time due to their structure and how they are metabolized in the body. They are made up of sugar molecules that can be rapidly broken down during digestion to glucose, which is the primary source of energy for the body's cells.

When carbohydrates are consumed, they are either used immediately for energy or stored in the liver and muscles as glycogen for later use. However, the reserves of glycogen are limited, which is why the energy from carbohydrates can diminish relatively quickly, especially during high-intensity activities or exercise.

In contrast, proteins are primarily used for building and repairing tissues rather than providing immediate energy, while fats serve as a more sustained and long-lasting energy source but are slower to metabolize. Vitamins do not provide calories and are essential for various metabolic processes but do not directly supply energy. These differences highlight why carbohydrates are particularly effective for immediate energy needs, making them the correct choice for this question.