Clenbuterol (http://www.isteroids.com/steroids/Clenbuterol.html) has been used for literally decades in the foreign veterinary world, for increasing the lean yield of livestock. It is clearly a very effective agent for this purpose, although its long half-life and tendency to stay active in the body for long periods of time mean that vets in the United States aren't able to use it. This is also the reason why (although it's an asthma medication) it's not available to asthmatics in the US of A. Albuterol is Clen's shorter acting cousin, and that's the FDA's drug of choice here. But in the world of athletics, Clenbuterol has a much longer history of use.

Clenbuterol (http://www.isteroids.com/steroids/Clenbuterol.html) is quite anti-catabolic and/or anabolic in almost every (animal) study ever done on it, although this hasn't been studied or confirmed in human studies (3). Also, a trend we see with Clenbuterol administration in animals is that the doses used are very high- more than anyone I've ever heard of actually taking. So, what I'm saying is that if Clenbuterol is anabolic or anti-catabolic in humans, only mild anabolic or anti-catabolic effects can realistically be expected.