Disclosed are the novel compounds as growth hormone secretagogues represented by structural Formula (I), wherein R¹ is, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted amino, X is —CO— or —SO₂—, Y is Formula (II), wherein n is an integer from 0-4, R⁴ is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, R⁵ and R⁶ are independently selected from hydrogen, substituted or unsubstituted alkyl, or R⁵ and R⁶ or R⁴ and R⁵ are taken together to form substituted or unsubstituted alkylene, R² is hydrogen, or substituted or unsubstituted alkyl, R³ is substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, D is substituted or unsubstituted amino, substituted or unsubstituted alkoxy, or substituted or unsubstituted alkylthio, * represents an asymmetric center, and pharmaceutically acceptable salts and individual isomers thereof, which have growth hormone releasing activity in humans or animals.