Question

Maximum amount of energy/ATP is liberated on oxidation of

• A. fats
• B. proteins
• C. starch
• D. vitamins

Answer 1

The Correct Option is A

To determine which of the given options liberates the maximum amount of energy/ATP upon oxidation, we need to understand the basic energy metabolism of different macronutrients in the body. The primary macronutrients that provide energy are carbohydrates, proteins, and fats. Vitamins, while essential for metabolism and various bodily functions, do not provide energy directly.

1. Fats:
   • Fats, also known as lipids, are a dense source of energy. They provide approximately 9 kilocalories (kcal) per gram, which is more than double the energy provided by carbohydrates or proteins.
   • The oxidation of fats occurs through a process called beta-oxidation, where long-chain fatty acids are broken down into acetyl-CoA units, entering the citric acid cycle and the electron transport chain, ultimately leading to the production of ATP.
   • This makes fats the most energy-rich macronutrient.
2. Proteins:
   • Proteins provide approximately 4 kcal per gram.
   • They are mainly used for building and repairing tissues, and their complete oxidation to release energy is not as efficient as fats.
   • During prolonged fasting or when carbohydrate and fat stores are low, proteins may be used, but they are not the primary source of energy under normal circumstances.
3. Starch (Carbohydrates):
   • Starch is a type of carbohydrate and provides about 4 kcal per gram.
   • Carbohydrates are the body's preferred energy source, especially during short bursts of activity, because they are easily converted to energy through glycolysis.
   • However, they do not provide as much ATP per gram as fats do.
4. Vitamins:
   • Vitamins do not provide energy. They are crucial as co-factors in enzymatic reactions involved in energy metabolism, but they do not themselves yield ATP upon oxidation.

Based on this analysis, fats are the macronutrient that liberates the maximum amount of energy/ATP upon oxidation. This makes option "fats" the correct answer. They provide more than twice the energy per gram compared to proteins and carbohydrates.

Thus, the correct answer is: fats.