c. 1400, "act of eating; act of regulating food intake according to regimen," verbal noun from diet (v.).
Entries linking to dieting
diet v.
late 14c., "to regulate one's diet for the sake of health," from Old French dieter, from diete "fare" (see diet (n.1)); meaning "to regulate oneself as to food" (especially against fatness) is from 1650s. Related: Dieted; dieting. An obsolete word for this is banting.