**4. Protein malnutrition post bariatric surgery**

Protein malnutrition remains the most serious macronutrient complication associated with malabsorptive surgical procedures. It can occur in up to 15% of patients after BPD/DS [43]. Studies reported that 3·0–18·5% of BPD/DS patients required reversal of their procedure because of protein malnutrition or excessive weight loss, or both [44]. Protein malnutrition can also occur after RYGB specially when the Roux limb exceeds 150 cm, where the reported prevalence is 9% at 2 years after surgery [43]; however protein malnutrition rarely necessitates reversal or conversion of a RYGB. It is also less common after LSG and LAGB, and in such cases it is likely due to maladaptive eating behaviors after surgery, especially in patients who avoid protein food sources or have protracted vomiting [6]. The clinical presentation of protein malnutrition includes edema, fatigue, skin, hair, and nail problems [6]. Because protein level often remains in the normal range until late, monitoring the serum albumin concentration is more useful for the assessment of the protein nutritional status. Patients with severe protein malnutrition should be treated with protein supplements that are rich in branch-chain amino acids and, in severe cases enteral feeding is recommended [6]. For prevention of protein malnutrition, an average daily protein intake of 60–120 g (1.1 g/kg of ideal body weight) is required and should be increased by 30% for patients post BPD/BD [16].
