Lacking p. pr. & vb. n. : of Lack

Example:
What would I Lacking in my diet to be constantly craving sushi?

Taxonomy
Merriam-Webster Online Dictionary, Dictionary, webster, Word Games, Webster Online Dictionary with audio pronunciations, Custom Search, glossary, english, language, ESL, Search, 1lack, lak, 13th century, intransitive verb, deficient, explanation, advisers.

Defination from the web:
lack from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... 1 : to be deficient or missing <time is lacking for a full explanation> ...