Two studies (one positive-quality longitudinal study and one positive-quality RCT) suggest that patients receiving HCT for hematologic malignancies require, on average, 35-40 kcal per kg per day to maintain nitrogen balance and body weight during the first month post-transplant. However, energy requirements may be higher during acute GVHD and for patients receiving > 75% of their total daily energy intake via PN. These studies evaluated patients receiving myeloablative allogeneic HCT, and energy needs may be different for patients receiving non-myeloablative and/or autologous HCT.