5 8 and 145 pounds is skinny as a rail. I am 5 6 and 198.. the only way i could get down to the 140's is if i did cardio for an hour everyday and started eating bird food.
his problem is he doesn't know how to eat and he also does too much cardio.. which is fine.. not everyone is a bodybuilder type. but why would you stick your nose into his business and try to get him to use AAS? he obviously isn't a bodybuilder so let him be.
btw I was an endurance athlete in my mid to late 20's and have numerous awards so don't think i don't know what your buddy looks like, he has a fit/runner look to him I GET IT and ITS OKAY!!.. lean muscle is not the same as muscle mass. lean muscle does not weigh much, but large muscle mass does. thats the difference. bottom line is diet and training will dictate if you have lean muscle or if you have large muscle mass. if you want large muscle mass you gotta train big and you gotta eat big.
i hate to put a number on it but i would say your friend should get to 170 pounds before he even thinks about AAS. atleast then he would of learned how to train and eat.. then he can take shit to another level. but large muscle mass takes time to build. he isn't gonna magically turn into a 200 pound beast overnight