Peptide GHK CU: Improving Loose Skin After Weight Loss PEPTIDE SPOTLIGHT: GHK Cu (Copper Peptide) Loose skin. Crepey texture. Dull, tired looking skin. Let's talk about the peptide that actually supports skin firmness from the inside out GHK Cu is Turn Back Time with GHK CU Peptides Meet one of the most powerful anti aging peptides in skincare GHK CU. This advanced peptide helps to: Tighten and firm loose skin GHK CU Peptide for Skin Rejuvenation Wittmer Rejuvenation Clinic GHK CU Crepey Skin Escape