The clearest wins are folate and vitamin D, on top of a healthy diet, a healthy weight, and not smoking
10.1016/j.ebiom.2018.12.062 105 WangL
Body Areas that Encounter Skin Pigmentation: Areas like elbows and knees are often pigmented, and you also get significant pigmentation on the toes where the footwear could be chafing against the skin
Researchers call this the "L-Arginine paradox" and attribute it to factors such as enzyme compartmentalization, the role of endogenous inhibitors (such as ADMA), and individual variation in amino acid metabolism
It might mean changing the agonist profile to engage slightly different receptor pathways
That said, GHK-Cu has a legitimate and valuable role in weight loss protocols, just not the role most people are searching for