Just like sucrose, the carbohydrate composition of high-fructose corn syrup is about half fructose and half glucose. The fructose and glucose in fruit, sucrose and high-fructose corn syrup gives your body four kilocalories of energy per gram of sugar, regardless of the source. Fructose and glucose are metabolized for energy in your cells through three sequential processes called glycolysis, the citric acid cycle and the electron transport chain. The energy is stored in a molecule called ATP. However, when your tissue ATP levels are high, instead of being metabolized for energy, fructose and glucose are converted into fatty acids that are assembled into triglycerides for tissue storage.