Which nutrient is primarily stored in the liver for energy?

The correct answer is carbohydrates, specifically in the form of glycogen. The liver plays a critical role in energy metabolism, and one of its primary functions is to store excess glucose as glycogen. When the body requires energy, particularly between meals or during physical exertion, the liver can convert glycogen back into glucose and release it into the bloodstream to maintain normal blood sugar levels. This process is vital for meeting the energy demands of the body, especially for the brain and muscles during activity.

In contrast to carbohydrates, proteins are primarily used for building and repairing tissues and are not mainly stored in the liver for energy. Instead, they can be converted into glucose through gluconeogenesis when necessary. Vitamins play essential roles in various biochemical functions but do not serve as direct energy sources or are stored primarily for that purpose. Minerals are crucial for numerous physiological processes but again do not function as energy sources nor are they stored for energy. Hence, carbohydrates are uniquely emphasized for their role in energy storage within the liver.