This invention relates to a colonic residue tagging system, formulation, kit and method for use in preparing an individual for a predetermined activity which requires tagging at least some colonic residue in a digestive tract such that a medically and/or diagnostically useful procedure can be performed on the digestive tract. Such predetermined activity includes, but is not limited to, colon screenings. In one alternative embodiment, a dietary regimen comprising low residue foods is coordinated with the colonic residue tagging regimen, prior to a predetermined activity, thereby resulting in tagged stool such that a medically or diagnostically useful procedure can be performed on the digestive tract. The present invention also provides an individual sufficient amounts of fluids and nutrition while minimizing the amount of stool formation prior to the predetermined activity. In another alternative embodiment, the foods comprise an effective amount of tagging agent, such that when the food is consumed over time, at least some of the colonic residue in the digestive tract will be sufficiently tagged so that a medically or diagnostically useful procedure can be performed on the digestive tract.