Methods to size a gastric pouch. In at least one embodiment for measuring the size of a gastric pouch of the present disclosure, the method comprises the steps of introducing a catheter into an esophagus, the catheter comprising an outer elongate tube, an inner elongate tube disposed within the outer elongate tube, a proximal balloon attached to the outer elongate tube, a distal balloon having a first end attached to the outer elongate tube and a second end attached to the inner elongate tube, at least two detection electrodes positioned on the outer elongate tube between at least two excitation electrodes, and a pressure transducer positioned on the outer elongate tube, locating the gastroesophageal junction using the proximal balloon, adjusting the distal balloon axially to a desired balloon length, injecting a fluid into the distal balloon to extend the distal balloon circumferentially, and determining a size variable of the gastric pouch.