Division of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA. Division of Neonatology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA. Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA. Department of Kinesiology, East Carolina University, Greenville, NC, USA.