Buon lavoro.

Siate razionali nell'alimentazione.

Non so quale sia il contesto, ma mi pare che "razionali", possa rendere in maniera abbastanza esauriente il termine "Sensibly".
spero di esserti di aiuto

Depending on the connotation of the text. This question gives me the chance to raise an issue of how to translate in Italian the English imperative or the direct you one finds in some circular letters, pamphlets, brochures and the like. It seems to me that the infinitive is more appropriate in Italian and that, in the second case, an impersonal construction is preferable. I don't have an example at hand for the second case, but I am sure that most of you have run into this problem
Saluti
Paola L M

Just another suggestion. The term "eat snsibly" could also be construed as meaning "eat healthily"

Good luck!