Will a BCAA powder make me gain weight? I mean this in the same way as creatine does, which when I took that I got really heavy and a bit fat in the space of a week. I’m not overly concerned about a small gain of lean muscle mass. I thought you guys would be the ones to answer this question as bodybuilders always know their diet and supplement shizzle. I’m a cross country runner hence not wanting to gain weight. I’m also a vegetarian. I have a very healthy diet and but thought a BCAA drink might help with muscle repair and make up for the gaps in my veggie diet.