As we age, the body undergoes many natural changes associated with aging skin. Genes determine the natural aging process (intrinsic aging), which cannot be altered, but there is a lot we can do to minimize the effects of premature skin aging (extrinsic aging) caused by our environment and lifestyle.
Intrinsic aging is characterized by decreased production of collagen and elastin (which give skin its strength and elasticity), decreased skin cell turnover (shedding of dead cells), and loss of fat beneath skin. These changes manifest as fine wrinkles, thin skin, hollowed cheeks and eye sockets, and sagging dry skin that may itch. These changes usually begin in our 20s, but they do not become noticeable until much later in life. There is little we can do to alter this process.
Extrinsic aging, on the other hand, is usually caused by the effects of the sun. It is also known as photoaging. These changes resemble the natural aging of skin, only that they appear much earlier in life. The damage caused by the sun is cumulative, meaning that your skin never forgets your tans and burns - even from your childhood! Your degree of premature skin aging thus depends on the total amount of sun you've received over the years. Smoking can also age skin by producing oxygen free radicals that cause premature wrinkles.