Sun damage can also lead to the appearance of thinning skin, as prolonged exposure to UV light breaks down the collagen and elastin proteins that give the skin its structure, strength and elasticity. Additionally, as we age, our bodies naturally begin to produce less hyaluronic acid, which has a plumping effect on the skin. Thus, you may notice that your face appears thinner as the amount of hyaluronic acid present in your skin declines. This can also contribute to the formation of facial lines and wrinkles.