Resting Energy Expenditure by Gastrointestinal Functional Status

Inclusion Criteria: Group A - Healthy Controls: * Age 18 to 65 years * No diagnosed chronic diseases * No hospitalization within the previous 30 days * No acute illness within the previous 14 days Group B - Participants With Intestinal Failure: * Age 18 to 65 years * Diagnostically confirmed intestinal failure * Stable clinical condition Exclusion Criteria: * Uncontrolled hyperthyroidism or hypothyroidism * Diabetes mellitus with poor glycemic control * Adrenal gland disease * Active inflammatory bowel disease, including Crohn's disease or ulcerative colitis * Celiac disease * Chronic pancreatitis * Active gastric or esophageal disease * Irritable bowel syndrome with significant symptoms * History of major abdominal surgery that permanently affects gastrointestinal function, except in participants with intestinal failure when this forms part of the condition under study * Heart failure * Active ischemic heart disease or recent myocardial infarction * Chronic obstructive pulmonary disease * Respiratory failure or need for long-term oxygen therapy * Progressive neurodegenerative disease * Dementia impairing the ability to participate * Severe stroke with significant functional impairment * Active tuberculosis * HIV/AIDS with clinically significant immunosuppression * Active systemic autoimmune disease * Active malignant disease * Advanced liver cirrhosis * Chronic kidney disease * Treatment with hemodialysis or peritoneal dialysis * Pregnancy or breastfeeding