Body weight (BW) changes for the gastric bypass (n = 18, ○) and sham-operated rats ad libitum fed (n = 12, ■) used for the 2-bottle preference test in the early phase (left) and body weight changes for the gastric bypass (n = 10, ○) and sham-operated rats ad libitum fed (n = 10, ■) used for the 2-bottle preference test in the late phase (middle) after surgery. Right: PYY and GLP-1 level for the gastric bypass (n = 9, white columns) and sham-operated rats ad libitum fed (n = 10, black columns) 200 days after surgery. Data are means ± SE (***P < 0.001).