The major culprit? A breakdown of collagen, which leads to a loss of elasticity. Peptides, a known collagen stimulant, are key to both La Mer The Regenerating Serum ($250; lamer.com) and Chantecaille Nano Gold Firming Treatment ($290; chantecaille.com). Meanwhile, hyaluronic acid, which can temporarily make skin look as if its collagen reserves have been replenished, is used in Shiseido Bio-Performance Super Corrective Serum ($80; sephora.com) and Olay Professional five-day Pro-X Intensive Firming Treatment, at right ($62; drugstore.com).
Photography by John Lawton