Question

Why Do Lipids Have a Higher Caloric Value Than Carbohydrates?

Answer 1

As we know that the calorific value is the amount of energy available from an item of food when digested, mostly from carbohydrates and fats. It is the amount of energy produced or released when fuel burns or any other substance is burnt in the presence of oxygen and the products of combustion are cooled to standard temperature pressure.

Complete answer:
Notably, all carbon atoms in glucose (a sugar) have an oxidation state of $- 1,0\,or\, + 1$, while all carbon atoms in palmitic acid (a fatty acid) have an oxidation state of $- 2\,or\, - 3$. This implies that the carbon atoms in fatty acids are surrounded by extra electrons. As explained in the Electrochemistry lesson, energy is released when electrons travel from an element with low electronegativities, such as carbon, to one with high electronegativities, such as oxygen. Thus, when the electrons around the carbon atoms in fatty acids are moved to oxygen (called oxidation), more energy is released than when the same process occurs with carbohydrates.
Also, Carbohydrates, proteins, and lipids account up $90\%$ of the diet's dry weight and $100\%$
of its energy. Each of these three sources of energy (measured in calories) has a different quantity of energy per gram ( $\dfrac{1}{{28}}$ ounce):
A gram of carbs or protein has four calories.
A gram of protein has 9 calories.
Additionally, these nutrients vary in terms of the rate at which they provide energy. Carbohydrates are the fastest metabolizers, whereas fats are the slowest.
Carbohydrates, proteins, and lipids are digested in the gut and broken down into their simplest units:
Carbohydrates are converted to sugars.
Proteins are broken down into amino acids.
Fats are broken down into fatty acids and glycerol.
The body utilizes these fundamental components to synthesize the chemicals required for development, maintenance, and activity (including other carbohydrates, proteins, and fats).
Perhaps, the amount of lipids saved as an energy reserve surpasses the amount of glycogen stored, since the human body cannot store as much glycogen as lipids. Carbohydrates provide just 4 kilocalories of energy per gram, while lipids provide 9 kilocalories per gram. When the electrons around the carbon atoms in fatty acids are transferred to oxygen, a greater amount of energy is freed than when the identical process happens with carbs.

Note:
Note that the existence of unoxidized carbon and hydrogen atoms determines the calorific value. The amount of heat energy that is present in food or fuel and which is determined by the complete combustion of a specified quantity occurring at constant pressure and in normal conditions is known as the calorific value.