Clenbuterol is a β2 adrenergic agonist with some similarities to ephedrine, but its effects are more potent and longer-lasting as a stimulant and thermogenic drug. It causes an increase in aerobic capacity, central nervous system stimulation, and an increase in blood pressure and oxygen transportation. It increases the rate at which fat and protein are metabolized, simultaneously slowing the body's BMR.
It is a banned drug for the bolded reasons. If he took Clenbuterol he was cheating. It is not approved for human use in Australia.
http://ndarc.med.unsw.edu.au/ndarcweb.nsf/resources/NDARCFact_Drugs2/$file/CLENBUTEROL+NDARC+FACT+SHEET.pdf
2 years.