beta-hydroxy beta-methylbutyrate, aka HMB plays a role in the synthesis of muscle tissue. I think it is more of an anti-catabolic supplement, rather than an anabolic one, since it ''spares'' the body braking down protein(aka muscle) which can happen after intense training sessions, first thing in the morning, when you miss a meal or get stressed out...HMB is a natural supplement, like creatine, it is produced in the body, but you only get results when supplementing with it, since our bodys dont produce any more that 1 gram of the stuff a day.
I have never tried the shit myself....
up to you, hope this helped!