Why are lipids so important to animal cells?

Lipids are fats, oils and waxes and are very significant
to animal cells. They can be used as an energy reserve and for insulation under the
skin, in the adipose tissue. The myelin sheath which surrounds the nerve cells contains
lipids. Lipids are important for the developing nervous system of a fetus. Lipids can be
converted into energy when needed and used in cellular respiration because they can be
broken down into acetic acid and enter the Krebs cycle to release high energy A.T.P.
molecules for cellular processes to proceed. Fat can be protective around certain areas
of the body; for example, women have a higher fat to muscle ration than men probably to
protect a developing fetus. Fats can store fat soluble vitamins, A, D, E, K in the
body.  Steroids in the body contain fats. Lipids are found in the double layered cell
membrane since it is composed of two layers of lipids and protein in
between.