The role of nutritional therapy (TN) in the surgical patient is well described in the literature and is associated with reductions in postoperative complications, length of hospital stay, and mortality. Adequate determination of caloric and protein requirements is an essential step in the TN institution, avoiding hypoalimentation and hyperalimentation. Thus, it is essential to understand the changes in energy expenditure after surgery and its relation with nutritional status. In addition, little is known about the effect of nutritional therapy and caloric adequacy on parameters such as phase angle and dynamometry. Thus, the objective of this study is to evaluate the changes in energy expenditure after major abdominal surgeries and to evaluate the phase angle and dynamometry as possible markers of nutritional therapy. Energy expenditure will be assessed by indirect calorimetry. Functionality will be assessed by means of dynamometry and 6-minute walk test. Nutritional diagnosis will be given through subjective global assessment. Energy and protein intake will be monitored and registered daily. Phase angle will be obtained by performing bioelectrical impedance.

Inclusion Criteria:

• Over 18 years old
• Patients admitted for major abdominal surgery
• Sign the consent form

Exclusion Criteria:

• Length of hospital stay less than 3 days
• Pregnancy
• Patients who, for any reason, can not perform indirect calorimetry

Patients undergoing major abdominal surgery at the University Hospital of University Federal of Minas Gerais