emaciation (n.)

"act of making lean or thin in flesh; state of becoming thin by gradual wasting of flesh, state of being reduced to leanness," 1660s, from Latin *emaciationem (nominative *emaciatio), noun of state from past-participle stem of emaciare "make lean, waste away," from assimilated form of ex "out" (see ex-) + macies "leanness," from macer "thin" (from PIE root *mak- "long, thin"). Or perhaps the noun is a native formation from emaciate (v.).