As we get old or gain and lose weight, our skin loses elasticity, tone and texture in general because of the decrease in collagen, elastin and subcutaneous fat which are the building blocks of a young skin.
Some of the signs of an aging skin are:
Thin lines and wrinkles
Skin laxity
Age spots
Hyperpigmentation
Under-eye dark circles
Sun damage
Purpose of a whole skin rejuvenation is to achieve a younger and smoother skin.