I think 'damage' is the wrong term. Coke/crack is an appetite suppressant, when on it you don't eat much and you certainly don't eat well. When you clean up, your appetite will return and weight gain is possible, but as far as physiological damage to one's metabolism, I don't see how that would fly. It's just been altered. Coming off crack means letting one's body readjust to its previous metabolic functions.
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