This is a Randomized Controlled Trial . The purpose of this study is to assess the hypothesis that whether a high protein diet combined with a physical activity protocol in surgical cancer patients admitted to the ICU in the post operative period is associated with better physical function at the hospital discharge as well as a better quality of life.

Surgical cancer patients will be categorized by their nutritional risk using a specific screening toll. During the hospital stay some measurements will be done. Such as resting energy expenditure (REE) before and after surgery; physical function evaluation; strength and quality of life.

The proposed intervention is a post operative diet with a different amount of protein (diet with a standard amount of protein and a diet with high amount of protein) associated to an institutional protocol of physical activity.

Inclusion Criteria:

• Cancer patients
• Age greater than or equal to 18 years old
• Have a tendency to be admitted to the ICU after the surgery
• Fill the eligible criteria to start enteral feeding within 72 hours
• Sign the consent form;

Exclusion Criteria:

• Mechanical ventilation such as fraction of inspired oxygen inspired oxygen fraction (FiO2) >60% or positive end expiratory pressure (PEEP) > 12cm H2O
• Bronchopleural fistula
• Karnofsky <50
• Participant cannot b enrolled in another study