We studied 21 patients with Guillain-Barré syndrome who demonstrated multiple nutritional risk factors upon admission to an intensive care unit: ventilator dependence (71.4%), adynamic ileus (23.8%), significant weight loss in the 2 weeks before admission (53.0%), antecedent viral illness with gastrointestinal sequelae (43.0%), cranial nerve deficits impairing oral intake and gastrointestinal motility (60%), and depressed serum transferrin (85.7%). Patients are hypermetabolic and hypercatabolic because of endocrine, infectious, and inflammatory components of the disease. High-energy (40 to 45 nonprotein kcal/kg), high-protein (2.0 to 2.5 g/kg) nutrition support appears to exert a favorable effect on visceral protein repletion, nitrogen balance, and resistance to pulmonary infection. Immediate attainment of positive energy balance in these hypermetabolic patients, ideally assessed by indirect calorimetry and followed by high-energy, high-protein feedings, may promote positive nitrogen balance early and attenuate muscle wasting in Guillain-Barré syndrome.