bulk(redirected from bulk up)
Also found in: Dictionary, Thesaurus, Legal, Idioms, Encyclopedia.
v. bulked, bulking, bulks
See dietary fiber.
verb To enhance one’s muscle mass by mechanics and/or chemistry
1. In nutrition, a substance that absorbs water in the intestinal tract. The increased mass helps to stimulate peristalsis. Bulk materials include bran cereals, cellulose, lignins, and psyllium. They are used therapeutically to treat constipation and other bowel disorders.
2. A mass; a large volume of cells, such as might be found in a tumor.