A thermoplastic starch for use in a melt-processed composition (e.g., fiber, nonwoven web, etc.) is provided. The thermoplastic starch contains an enzymatically debranched starch and a plasticizer. By selectively controlling certain parameters of the enzymatic modification process (e.g., temperature, enzyme and starch concentrations, reaction time, isolation method, etc.), the present inventors have discovered that a native starch may be hydrolyzed in a highly efficient manner to form compositions having a comparably lower weight average molecular weight and viscosity, which are particularly suitable for use in the formation of thermoplastic starches for use in melt processing applications.