bulk out

bulk out (third-person singular simple present bulks out, present participle bulking out, simple past and past participle bulked out)

1. (intransitive) To become thicker, fatter or more bulky.
2. (transitive) To cause to be thicker, fatter or more bulky.
3. (intransitive) To become more substantial
4. (transitive) To cause to be more substantial; to add substance to.

   The pet food was made from meat bulked out with rusk.

• outbulk