Popular places on the body for contouring treatments include the hips, thighs, buttocks and abdomen. One reason for this is that the hips, thighs and buttocks are areas particularly prone to cellulite. Cellulite is a term used to define the puckered, dimpled or “orange peel”-like appearance of the skin often seen in these areas of the body. Cellulite typically begins to develop during or after puberty, so it is thought that estrogen plays a role in its development.1
Cellulite can manifest in women of all ages, races and body weights. Although weight gain can worsen the appearance of cellulite, it is noteworthy that even slender women can suffer from the appearance of cellulite.2 ,3 Thus, it is not surprising that the hips, thighs and buttocks are sites that are also popular targets for slimming treatment products.
Skin structure considerations
The outer layer of the skin reflects activity beneath its surface, especially when structural changes are occurring. Therefore, to best understand how to target slimming formulations to these areas, it is worthwhile to understand a bit more about the underlying anatomy.
The skin is composed of the epidermis and the dermis. Underlying the dermis is the hypodermis, or subcutaneous fat layer. The subcutaneous fat layer can be thought of as being composed of two sub-layers. These two sub-layers include the deeper localized fat deposits and the more superficial compartmentalized layer of fat.
Localized fat deposits typically are the targets of liposuction. Cellulite appears to originate in the fat layer where structural compartmentalization of adipose, or fat tissue, is predominant.4-6 Small, upright chambers are encircled and separated by vertical bands of connective tissue (CT), referred to as septa. The compartments are anchored to the dermis above and the tissue below. Overall, the appearance of the compartments can be described as somewhat honeycomb.
When the fat cells in these chambers become enlarged and fluid accumulates there, the chambers begin to bulge, pressing against the septa. This bulging phenomenon of the septa contributes toward the appearance of dimples and bumps on the surface of the skin in cellulite.6 With age and sun damage, the septa, composed principally of collagen, can become further weakened and thickened, resulting in shrinkage.6-8 As the septa shrink and pull on the underlying anchors of the chambers, this also can contribute to the indentations seen on the surface of the skin in cellulite. 6-8
Another hypothesis regarding cellulite notes that an inflammatory process caused by decreased circulation may also be involved. It is believed that the early structural changes leading to cellulite formation are the result of decreased circulation, which itself is the direct result of deterioration of the dermal blood vessels—especially a loss of the capillary networks.8 The loss of the capillary networks has been hypothesized to be caused by engorged fat-storing cells, called adipocytes, joining together and inhibiting venous return.
Clearly, there are a number of targets that slimming treatments can address. These areas include: enhancing the removal of fluid buildup by improving microcirculation to the areas in question; strengthening the CT while protecting it from further degradation caused by inflammation and the subsequent release of matrix metalloproteinases (MMPs), which are capable of degrading all kinds of extracellular matrix proteins; and targeting the adipose tissue via stimulation of adipocyte cell metabolism, thermogenesis or some other mechanism to decrease adipocyte contents—lipolysis, or the breaking down of fat stored in cells. Traditional and newer approaches to slimming treatments use a number of ingredients to achieve such ends, described below.9–14