What Is the Major Source of Energy for Body Cells?

Carbohydrate, fat and protein molecules are the three energy-containing molecules in food. Of these three molecules, the sugar obtained from carbohydrates (called "glucose") functions as the major source of energy for the body's cells.

Features

• The energy contained in food is stored in the chemical bonds of the atoms that form each molecule of carbohydrate, fat or protein. The processes of digestion and cellular respiration work to break down these molecules into smaller and smaller components until this chemical bond is finally broken, and the energy bound within it is released and used to synthesize ATP (adenosine triphosphate).

Function

• ATP is a high-energy phosphate bond that transports energy throughout the cell. It is the energy that actually powers the cell.

Basis

• Each energy molecule follows a different catabolism pathway to ATP production. One of the reasons glucose is the cells' primary energy source is because it follows the most efficient pathway. Fat molecules are more difficult to catabolize, and the breakdown of proteins is generally for the purpose of synthesizing other proteins.

Effects

• Despite the hype of low-carbohydrate diets, to function most effectively, the body actually needs a significant amount of carbohydrate calories.

Recommendation

• The Mayo Clinic guidelines recommend that 45 to 65 percent of your daily caloric intake be derived from carbohydrates.