Don't know about other states but in SC here is one of the shoplifting statutes about concealing merchandise-
SECTION 16-13-120. Shoplifting; presumptions from concealment of unpurchased goods.
It is permissible to infer that any person wilfully concealing unpurchased goods or merchandise of any store or other mercantile establishment either on the premises or outside the premises of the store has concealed the article with the intention of converting it to his own use without paying the purchase price thereof within the meaning of Section 16-13-110. It is also permissible to infer that the finding of the unpurchased goods or merchandise concealed upon the person or among the belongings of the person is evidence of wilful concealment. If the person conceals or causes to be concealed the unpurchased goods or merchandise upon the person or among the belongings of another, it is also permissible to infer that the person so concealing such goods wilfully concealed them with the intention of converting them to his own use without paying the purchase price thereof within the meaning of Section 16-13-110.
So I would guess if one ate food before paying for it in a "store" then one is guilty of shoplifting. It is concealed in ones stomach right
One can't produce it in its original form and claim you were going to pay for it, and it was concealed

SECTION 16-13-120. Shoplifting; presumptions from concealment of unpurchased goods.
It is permissible to infer that any person wilfully concealing unpurchased goods or merchandise of any store or other mercantile establishment either on the premises or outside the premises of the store has concealed the article with the intention of converting it to his own use without paying the purchase price thereof within the meaning of Section 16-13-110. It is also permissible to infer that the finding of the unpurchased goods or merchandise concealed upon the person or among the belongings of the person is evidence of wilful concealment. If the person conceals or causes to be concealed the unpurchased goods or merchandise upon the person or among the belongings of another, it is also permissible to infer that the person so concealing such goods wilfully concealed them with the intention of converting them to his own use without paying the purchase price thereof within the meaning of Section 16-13-110.
So I would guess if one ate food before paying for it in a "store" then one is guilty of shoplifting. It is concealed in ones stomach right