It worked for me getting some better sleep (not as good as GHB though), I doesn't do anything directly for fatburning or muscle growth. Indirectly yes, if your sleep quality becomes better. BTW I got a strange sensation in my hands after using it...
I believe there are a couple of Italian studies showing increased growth hormone release.
GABA does not readily cross the blood brain barrier (which is why they invented GHB), so it is a bit surprising that it would increase it.
It does metabolize to GHB in the brain, perhaps it does peripherally as well. Though, subjectie description of its psychoactive effects do not match those of GHB.
to be honest i never heard of this stuff. what i do for products i've never heard of is (after checking out these boards) i go to google and search for articles done on the stuff by people OTHER than the makers or advertisers. people who have nothing to gain by promoting it.