Final answer:
Carbohydrates and lipids are the two macronutrients that provide the best energy, with carbohydrates offering quick energy and lipids providing long-term energy storage.
Step-by-step explanation:
The two macronutrients that provide the best energy are carbohydrates and lipids (fats and oils). Carbohydrates provide about 4 Calories per gram and are the body's preferred source of quick energy. In comparison, lipids provide a higher amount of energy, about 9 Calories per gram, and they are crucial for long-term energy storage. While proteins also provide about 4 Calories per gram, their primary role is to supply amino acids for the building blocks of the body rather than serving as a primary energy source.
When you eat foods containing carbohydrates and lipids, the digestive system breaks them down into molecules small enough to be absorbed and metabolized into ATP (adenosine triphosphate), which is the energy currency of the cell. Therefore, even though all macronutrients except water can be metabolized for energy, carbohydrates and lipids are specially considered the energy-yielding nutrients.