Question

How do lipids store energy?

Answer 1

See Below

Explanation:

Burning a sample that contains carbon (in presence of oxygen) is called a combustion reaction. It is also an oxidation reaction.

`CH_4 + 2O_2 = CO_2 + 2H_2O`
The oxidation state of C in `CH_4` is -4
The oxidatoin state of C in "CO_2" is +4
This is a total of 8 electrons that have to change hands, and much of the energy in this process is associated with the electrons (Electron Transport chain and oxidation phosphorylation in cells).

Fats have many carbons that look like the above Carbon.
`-CH_2-` is a typical fat carbon. When this gets oxidized to `CO_2`, the carbon goes from a -2 oxidation state to a +4 oxidation state. Exchange of 6 electrons.

Sugars are another source of energy, but not a good storage of energy. The carbon in Sugar makes less energy when it is oxidized.
`H-C-OH` This is a typical carbon in a sugar. It has a 0(zero) oxidation state. When it gets oxidized to `CO_2`, it goes to a +4 oxidation state. This is 4 electrons changing hands.

As a result, more electrons are liberated when fats burn than when sugars burn. This makes fats a better store of energy.