The metabolic response to ulcerative colitis, including increased proteolysis and lipolysis and changes in energy expenditure, plays a significant role in the resulting malnutrition from which these patients suffer. Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, has been found to be elevated in children with ulcerative colitis. TNF-alpha has been incriminated in the mechanism of weight loss in many different chronic diseases, and causes net protein and lipid catabolism. Anti-TNF-alpha antibody (infliximab) has been proven to be an effective therapy for ulcerative colitis.||The purpose of this study is to determine changes in protein and lipid metabolism, as well as resting energy expenditure, before and after therapy with anti-TNF-alpha antibody (infliximab) in children with ulcerative colitis. Performing this study will better define the changes in nutrition status observed in these children following remission of active ulcerative colitis, and potentially lead to changes in medical and nutritional management of these children