One plausible explanation - which also explains why very few men suffer from cellulite  - is based on the composition and behavior of a woman's fat cells and the connective tissue that holds them in place.  Very simply, a woman's connective tissue is very inflexible, as a female gains weight their fat cells expand, and tend to bulge upwards towards the surface of the skin, giving the classic orange-peel appearance of cellulite.  Women also have an additional layer of fat for childbearing purpose.  In men, not only is there generally less fat on the thighs, but also the outer skin is thicker and thus obscures what is happening to any surplus fat below.

The causes are poorly understood, and several changes in metabolism and physiology may cause cellulite or contribute to cellulite.  Among these are a disorder of water metabolism, abnormal hyper-polymerization of the connective tissue, and chronic venous insufficiency.

Hormones play a dominant role in the formation of cellulite.  Estrogen is the most important hormone.  It seems to initiate and aggravate cellulite.  Other hormones including insulin, the catecholamine, adrenaline, and noradrenalin, thyroid hormones, and prolactin have all been shown to participate in the development of cellulite.

Diet has been shown to affect the development and amount of cellulite in the body.  Excessive amounts of fat, carbohydrates, salt, or too little fiber can all contribute to increased cellulite.  This also includes the accumulation of toxins built up between the fat cells, toxins enter the body from chemicals in our food, water, and air along with skin creams and shampoos (it has been noted that "Paraben" found in skin creams and shampoo can lead to Thyroid dysfunction).

Smoking, lack of exercise, fatty/starchy foods, and sitting or standing in a single position for long periods have all been correlated with an increase in cellulite.  A high stress lifestyle will increase in the catecholamine hormones.