What is a major source of energy for the human body?

Carbohydrates serve as a major source of energy for the human body. When consumed, carbohydrates break down into glucose, which is the simplest form of sugar. This glucose is utilized by the body's cells as a primary energy source for various physiological functions, including brain activity, muscular exertion, and overall metabolic processes.

When glucose levels in the blood rise, the hormone insulin is released to facilitate the uptake of glucose into the cells, where it can be used immediately for energy or stored as glycogen in the liver and muscles for later use. This quick conversion and availability make carbohydrates particularly important for providing immediate energy, especially during high-intensity physical activities.

While fats and proteins can also provide energy, they are not the body's preferred or primary sources under normal circumstances. Fats serve as a secondary energy source and are more efficient in terms of energy content, but they take longer to metabolize. Proteins are mainly used for building and repairing tissues and, while they can be converted into glucose when carbohydrates are not available, this process is not as efficient as using carbohydrates directly. Vitamins, on the other hand, do not provide energy, but they play essential roles in metabolic pathways that utilize energy from macronutrients.