Batu,
Steroids such as anabolic steroids ( eg Deca-Durabolin, Sustanon 250 etc...) are man-made chemicals that'll help someone build muscle while losing fat. However, I wouldn't recommend it cos you might lose your medical, according to the guys above, and also did you know that they have the 'power' to shrink organs in which they have affinity with?
You got to be joking...