In this tissue the intracellular substance is reduced, and the lipid-rich cells are called adipose cells.
It occurs mainly under the skin, performing functions of energy reserve, protection against mechanical shocks and thermal insulation. It also occurs around some organs such as the kidneys and the heart.
Fat cells have a large central fat vacuole, which increases or decreases, depending on metabolism: if a person eats little or consumes a lot of energy, fat from fat cells decreases; otherwise it accumulates. Fat tissue acts as an energy reserve for times of need.