This invention provides: 1) a method of treating a subject suffering from a muscle wasting disorder; 2) a method of preventing a muscle wasting disorder in a subject; 3) a method of treating, preventing, suppressing, inhibiting or reducing muscle loss in a subject suffering from a muscle wasting disorder; 4) a method of treating, preventing, inhibiting, reducing or suppressing muscle wasting in a subject suffering from a muscle wasting disorder; and/or 5) a method of treating, preventing, inhibiting, reducing or suppressing muscle protein catabolism in a subject suffering from a muscle wasting disorder, by administering to the subject a selective androgen receptor modulator (SARM) and/or its analog, derivative, isomer, metabolite, pharmaceutically acceptable salt, pharmaceutical product, hydrate, N-oxide or any combination thereof, as described herein.