A compound for use in for reducing skeletal muscle atrophy or for therapeutic use in promoting skeletal muscle hypertrophy in an animal, the compound being of formula I wherein: R 1 is chosen from OR 2 and NHR 3 ; R 2 is H or acetyl; R 3 is chosen from -(CH 2 ) n OH and -(CH 2 CH 2 O) n H; G is (C 2 -C 10 )hydrocarbyl; R 4 is H or (C 1 -C 3 )hydrocarbyl; and R 5 is chosen from H, (C 1 -C 10 )hydrocarbyl, fluoro(C 1 -C 6 )alkyl, and -C(=O)R 6 , wherein R 6 is chosen from H, (C 1 -C 10 )aliphatic hydrocarbyl, -O-(C 1 -C 10 )hydrocarbyl, -NH-(C 1 -C 10 )hydrocarbyl, substituted aryl, substituted arylalkyl, heterocyclyl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl, -NH-(substituted aryl), -NH-(substituted arylalkyl), -NH-(heterocyclyl), and -NH-(substituted heteroaryl); wherein substituents on aryl and heteroaryl are chosen from halogen, halo(C 1 -C 6 )alkyl, (C 1 -C 6 )alkyl, (C 1 -C 6 )acyl, (C 1 -C 6 )alkoxy(C 1 -C 6 )alkyl, hydroxy(C 1 -C 6 )alkyl, phenyl, heteroaryl, benzenesulfonyl, hydroxy, halo(C 1 -C 6 )alkoxy, (C 1 -C 6 )oxaalkyl, carboxy, (C 1 -C 6 )alkoxycarbonyl [-C(=O)O-alkyl], (C 1 -C 6 )alkoxycarbonylamino [ HNC(=O)O-alkyl], carboxamido [-C(=O)NH 2 ], (C 1 -C 6 )alkylaminocarbonyl [-C(=O)NH-alkyl], cyano, acetoxy, nitro, amino, (C 1 -C 6 )alkylamino, di(C 1 -C 6 )alkylamino, di(C 1 -C 6 )alkylamino(C 1 -C 6 )alkyl, mercapto, (C 1 -C 6 )alkylthio, (C 1 -C 6 )alkylsulfone, sulfonylamino, (C 1 -C 6 )alkylsulfinyl, (C 1 -C 6 )alkylsulfonyl, (C 1 -C 6 )acylamino(C 1 -C 6 )alkyl, (C 1 -C 6 )acylamino, amidino, heterocyclyl, phenoxy, benzyloxy, heteroaryloxy, hydroxyimino, alkoxyimino, aminosulfonyl, guanidino and ureido; and n is 2-6. R 1 is chosen from OR 2 and NHR 3 ; R 2 is H or acetyl; R 3 is chosen from -(CH 2 ) n OH and -(CH 2 CH 2 O) n H; G is (C 2 -C 10 )hydrocarbyl; R 4 is H or (C 1 -C 3 )hydrocarbyl; and R 5 is chosen from H, (C 1 -C 10 )hydrocarbyl, fluoro(C 1 -C 6 )alkyl, and -C(=O)R 6 , wherein R 6 is chosen from H, (C 1 -C 10 )aliphatic hydrocarbyl, -O-(C 1 -C 10 )hydrocarbyl, -NH-(C 1 -C 10 )hydrocarbyl, substituted aryl, substituted arylalkyl, heterocyclyl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl, -NH-(substituted aryl), -NH-(substituted arylalkyl), -NH-(heterocyclyl), and -NH-(substituted heteroaryl); wherein substituents on aryl and heteroaryl are chosen from halogen, halo(C 1 -C 6 )alkyl, (C 1 -C 6 )alkyl, (C 1 -C 6 )acyl, (C 1 -C 6 )alkoxy(C 1 -C 6 )alkyl, hydroxy(C 1 -C 6 )alkyl, phenyl, heteroaryl, benzenesulfonyl, hydroxy, halo(C 1 -C 6 )alkoxy, (C 1 -C 6 )oxaalkyl, carboxy, (C 1 -C 6 )alkoxycarbonyl [-C(=O)O-alkyl], (C 1 -C 6 )alkoxycarbonylamino [ HNC(=O)O-alkyl], carboxamido [-C(=O)NH 2 ], (C 1 -C 6 )alkylaminocarbonyl [-C(=O)NH-alkyl], cyano, acetoxy, nitro, amino, (C 1 -C 6 )alkylamino, di(C 1 -C 6 )alkylamino, di(C 1 -C 6 )alkylamino(C 1 -C 6 )alkyl, mercapto, (C 1 -C 6 )alkylthio, (C 1 -C 6 )alkylsulfone, sulfonylamino, (C 1 -C 6 )alkylsulfinyl, (C 1 -C 6 )alkylsulfonyl, (C 1 -C 6 )acylamino(C 1 -C 6 )alkyl, (C 1 -C 6 )acylamino, amidino, heterocyclyl, phenoxy, benzyloxy, heteroaryloxy, hydroxyimino, alkoxyimino, aminosulfonyl, guanidino and ureido; and n is 2-6. <EOS>