Blood collection and enzyme-linked immunosorbent assay
Participants were seated, and approximately 5 mL of venous blood was drawn from the anterior cubital vein by venipuncture. The blood sample was collected in a heparin anticoagulant tube and centrifuged at 2000 g for 10 min at 4 °C. Then, the upper plasma layer was extracted and stored in a refrigerator at -80 °C. The total ghrelin (Millipore, Burlington, USA; % coefficient of variation (CV): 6.2%) and peptide YY (PYY) (Millipore, Burlington, USA; %CV: 4.8%) in the extracted sample were determined using radio-immunoassays, while glucagon-like peptide-1 (GLP-1) (Cusabio; %CV: 5.7%) and high sensitivity interleukin-6 (IL-6) (Multi science, Hangzhou, China; %CV: 6.7%) was measured using ELISA.