I would swear by BCAA's if it worked for me, but most of my fitness friends go that route. I am 6'2", 176 and have been around that size since high school. In mid-forties now.
I have had many coaches try to bulk me up and every plan has failed, even lost pounds on a few programs. I have long since given up on adding more muscle. I can eat whatever I want and gain nothing
Over the years, the only fat I have gained is a bit in the abdomen(from alcohol) which is barely noticeable. I want to tone up some more but it seems my metabolism won't allow me.
I might try one more time but it will be pointless.........