This prospective, comparative interventional study will evaluate resting energy expenditure in adults with different gastrointestinal functional status. A total of 92 participants aged 18 to 65 years will be included: 30 healthy adults with normal gastrointestinal function and 62 patients with clinically confirmed intestinal failure. The intestinal failure group will include patients with short bowel syndrome and patients with other causes of intestinal failure.

Participants will be assigned to one of two protocol-defined groups according to their gastrointestinal functional status. Each participant will attend one study visit lasting approximately 90 to 120 minutes. The research procedures will include measurement of resting energy expenditure by indirect calorimetry after an overnight fast, assessment of body composition by dual-energy X-ray absorptiometry and bioelectrical impedance analysis, and blood sampling for inflammatory markers.

The primary objective is to compare resting energy expenditure between healthy participants and patients with intestinal failure and to determine whether resting energy expenditure differs according to the underlying cause of intestinal failure. Secondary objectives are to evaluate the associations between resting energy expenditure, lean body mass, fat mass, phase angle, and inflammatory markers. The results may contribute to more individualized nutritional management of patients with intestinal failure.