Cellulite is a condition characterized by portions of subdermal adipose fat-containing tissue that migrate into and through the subdermal elastic tissue matrix. Cellulite appears due to the protrusion of pockets of depot fat from subcutaneous tissue through an elastic layer of connective tissue overlying the depot fat into the dermis.

Patients having cellulite appear to exhibit a deficiency in the fibrous layer at the interface between the dermis and the subcutaneous tissue. This deficiency allows depot fat below the interface to protrude through the fibrous layer and into the dermis, thereby causing irregular elevations and depressions of the dermis characterized by a "dimpled" appearance.

Cellulite is not a unique substance; indeed, it is no different from fat cells found in any other part of the body. Fat cells have fat-storing and fat-releasing receptor sites. Different parts of the body are characterized by fat cells with more fat-storing sites or more fat-releasing sites. The distribution of adipose tissue throughout the body is not uniform. In certain portions of the body, such as the subcutaneous tissue, adipose tissue is present in great abundance. Adipose tissue consists of small vesicles or "fat cells" lodged within a matrix of areolar connective tissue. In many parts of the body, the areolae are occupied by fat cells. The matrix and fat cells constituting adipose tissue are referred to as "depot fat".

In cellulite, fat is stored in fat cells which lie between the skin and the underlying muscle. These fat cells are grouped together into large collections separated by fibrous strands (fibrous septae). These fibrous strands run between the muscle and the skin. In fact, fibrous septae surround and hold the fat in place in small compartments. As fat cells expand with weight gain, the gap between muscle and skin expands, but the fibrous strands cannot stretch and thus cannot support the skin. The skin is tethered down by string-like tissues that pull it inward, toward the interior of the body. The tension of these septae pulls in sections of fat along with them, causing the fat cells in the subcutaneous layer to increase in number and stick together within the connective tissue fibers, resulting in a dimpling effect ("orange peel" or "cottage cheese").