For more than 40 years the use of nonvolitional feedings (ie, enteral nutrition [EN] and parenteral nutrition [PN]) has been a mainstay of the medical nutrition therapy that registered dietitians (RDs) utilize for their hospitalized patients with limited or no gastrointestinal function. To date, the use of this therapy remains somewhat controversial, and some clinicians dispute that its risks and costs outweigh its benefits. This commentary will explore the findings of prospective randomized clinical trials that compared PN or EN to standard care (ie, normal, volitional dietary intake), cite specific reasons why these findings may have occurred, and discuss the potential contribution the RD can provide to optimize study designs for these types of investigations.