Your skin is made up of collagen and elastin, two proteins that provide skin with structure and its ability to “snap back.” However, as you age you begin to lose collagen in the face. This makes your skin less able to smooth out when the muscles underneath are relaxed. A reduction in collagen will also lead to less volume in your face. As a general rule, you lose about 1% of collagen per year. By 45, your face may lose up to 25% of collagen.