The Collaborative International Dictionary of English v.0.48:

Diet \Di"et\, v. t. [imp. & p. p. Dieted; p. pr. & vb. n.
   Dieting.]
   1. To cause to take food; to feed. [R.] --Shak.
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   2. To cause to eat and drink sparingly, or by prescribed
      rules; to regulate medicinally the food of.
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            She diets him with fasting every day. --Spenser.
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