If someone is asking about GHK-Cu specifically, the most practical ranking is usually abdomen first, outer thigh second, and upper arm third
10.1021/jf049583c 362
Improved energy levels: Optimal glutathione levels support cellular energy production, leading to increased vitality and reduced fatigue
Research in animal models suggests it could protect against cell aging and support long-term metabolic health
Remember, its not a complete cure for tiredness: good rest, sleep, and nutrition are also vital to fighting fatigue.
Additionally, studies have shown that antioxidant enzymes GPX4 and SOD1, along with the transcription factor NRF2, are involved in intracellular GSH redox reactions [29, 30]