How does beta oxidation compare to carbohydrate oxidation in terms of energy yield?

How does beta oxidation compare to carbohydrate oxidation in terms of energy yield?

• A. Fatty acid oxidation yields substantially more energy than carbohydrate oxidation
• B. They yield the same amount of energy
• C. Fatty acid oxidation yields less energy
• D. Fatty acid oxidation yields negligible energy

Answer: (A)

Fatty acids provide much more energy per molecule than carbohydrates because they are more reduced and yield more high-energy electrons during oxidation. In beta-oxidation, each two-carbon unit removed from a fatty acid produces one FADH2 and one NADH. Those reducing equivalents feed the mitochondrial electron transport chain, generating ATP. The two-carbon fragments become acetyl-CoA, and every acetyl-CoA entering the TCA cycle generates additional NADH and FADH2 (along with GTP). This combination of numerous acetyl-CoA units and repeated production of NADH and FADH2 leads to a much larger overall ATP yield. For example, a long-chain fatty acid like palmitate can yield on the order of about 100 ATP, whereas glucose oxidation yields about 30–32 ATP. In addition, fats store energy in a denser form, about 9 kcal per gram compared with 4 kcal per gram for carbohydrates, contributing to their higher energy yield.

Fatty acids provide much more energy per molecule than carbohydrates because they are more reduced and yield more high-energy electrons during oxidation. In beta-oxidation, each two-carbon unit removed from a fatty acid produces one FADH2 and one NADH. Those reducing equivalents feed the mitochondrial electron transport chain, generating ATP. The two-carbon fragments become acetyl-CoA, and every acetyl-CoA entering the TCA cycle generates additional NADH and FADH2 (along with GTP). This combination of numerous acetyl-CoA units and repeated production of NADH and FADH2 leads to a much larger overall ATP yield.

For example, a long-chain fatty acid like palmitate can yield on the order of about 100 ATP, whereas glucose oxidation yields about 30–32 ATP. In addition, fats store energy in a denser form, about 9 kcal per gram compared with 4 kcal per gram for carbohydrates, contributing to their higher energy yield.