An endoscopically-guided power-assisted tissue aspiration method of and system for safely removing fat tissue from the mesenteric region of a patient. The endoscopically-guided power-assisted tissue aspiration system includes: an endoscopy system having a video probe, one or more video monitors, and digital recording equipment; and a power-assisted tissue aspiration system including a powered hand-supportable instrument including a hand-supportable housing and being provided with a twin-cannula assembly including an inner cannula mounted for reciprocating movement within an outer cannula; a source of power operably connected to the powered hand-supportable instrument, for supplying power to drive the inner cannula to reciprocate said inner cannula within the outer cannula during tissue aspiration operations; and a vacuum pump operably connected to the inner cannula, for aspirating visceral fat tissue from the mesenteric region of the patient, through outer and inner aspiration apertures of the twin-cannula assembly, while the video probe is capturing digital images of fat tissue within the FOV, the video monitor is displaying the captured digital images of fat tissue being removed from the mesenteric region of the patient, and the digital recording equipment is recording the same.