To assess the correlation of body composition with the response and outcome of neoadjuvant treatment (NAT) in patients with pancreatic ductal adenocarcinoma (PDAC). One hundred and nineteen PDAC patients underwent curative resection after NAT. Computed tomography scans of the third lumbar vertebra were used to assess the body composition of these patients before and after NAT. Three distinct wasting phenotypes were identified during NAT, with 51 patients (42.9%) developing muscle and fat wasting (MFW), 17 patients (14.3%) developing fat-only wasting (FW), and 51 patients (42.9%) having no wasting (NW). The response rate was higher in the NW phenotype than in the MFW and FW phenotypes (P = 0.007). In univariate and multivariate analyses, histological grade, sarcopenia before NAT, and MFW during NAT were associated with decreased overall survival (OS). Sarcopenia before NAT and MFW during NAT were associated with decreased disease-free survival (DFS). Body composition was associated with the response and outcome of patients undergoing NAT for PDAC. The response rate was higher in patients having NW during NAT. Sarcopenia before NAT and MFW during NAT were associated with decreased OS and DFS.