Killing the fitness industry: Weight loss drugs promise a lifetime of injections Peptides are having a moment, but not all of them are harmless., One thats getting a lot of attention right now? Melanotan II., Its being used to achieve a tan from the inside, but what it Melanotan peptide might seem like the cool thing to doit makes you look tan., But these unregulated injections come with real risks., They can cause unpredictable skin changes, including darkening of Doctors warn against tan injections