Source : Webster's Revised Unabridged Dictionary (1913)

Dietetic \Di`e*tet"ic\, Dietetical \Di`e*tet"ic*al\, a. [Gr. ?:
   cf. F. di['e]t['e]tique. See {Diet}.]
   Of or performance to diet, or to the rules for regulating the
   kind and quantity of food to be eaten.

Source : WordNet®

dietetical
     adj : of or relating to the diet; "dietary restrictions" [syn: {dietary},
            {dietetic}]