Great question. Little time, so short answer: THG (tetrahydrogestrinone) is a steroid substance bearing similarities to gestrinone, a banned Olympic substance but not a controlled substance or "anabolic steroid" as defined by federal law. However, the FDA has formally declared that THG meets the definition of an unapproved drug. Therefore, it cannot at this time be purchased for human consumption in the U.S. and would now be illegal to sell for that purpose.