BACKGROUND: Little is known about factors associated with protein intake post-laparoscopic sleeve gastrectomy, especially in Chinese weight loss patients over 6 months. This project aimed to identify possible factors to improve protein intake and investigate protein supplement usage to reduce complications such as malnutrition. METHODS: A prospective observational study was conducted on 120 eligible patients at a tertiary hospital. They completed study measures at baseline, 3 months post-surgery (T0), and 6 months post-surgery (T1). Univariate and multivariate Linear regressions were utilized to analyze factors related to protein intake. RESULTS: At 6 months post-surgery, most patients did not meet the recommended protein intake of ≥ 60 g/day. Patients who intake protein <
60 g/day lost more weight at T0, but patients who intake protein ≥ 60 g/day lost more weight at T0 to T1. The three macronutrients for all patients were significant differences in dietary and protein supplement sources between T0 and T1. Multi-factor linear regression found that lower educational level, pre-operative hypertension, and the lower EBBS total score at 6 months were significant predictors of insufficient daily protein intake. CONCLUSIONS: Findings shed new light on factors that may account for deficiency protein intake, which have implications for guiding effective interventions targeting this behavior.