Katie carefully takes a syringe out of its packet. She pricks the top of a small jar of blue liquid and pulls the plunger up.
She turns and jabs the needle into her bum cheek and gives the camera a big thumbs up, looking pleased.
Katie's been injecting GHK-Cu, a copper peptide, for several weeks now and she's confident it's making a difference to her skin. So much so, she says, the stretch marks she developed after having her two children have almost disappeared.
The only disconcerting thing?
It clearly says "for research purposes only" on the label wrapped around the jar. This peptide is not suitable for human consumption.
