1. A medical image diagnosing support apparatus comprising: a first extraction means which extracts a body region of a subject from a tomographic image of the subject acquired by a medical tomographic apparatus and removes data of an epidermal tissue layer region from data of the body region; a second extraction means which automatically (a) searches the tomographic image for a predetermined range of CT values corresponding to an abdominal wall muscle layer to determine from a histogram of the CT values in the predetermined range a most frequently occurring CT value in the predetermined range, (b) sets a threshold by utilizing the most frequently occurring CT value in the predetermined range, (c) applies peripheral edge recognition processing to extract, while utilizing the threshold, an abdominal wall muscle layer region as a non-adipose region from the body region and determine position data for an outline surrounding the abdominal wall muscle layer region, wherein the data of the epidermal tissue layer region has been removed from the data of the body region, and (d) sets a line surrounding the abdominal wall muscle layer region, by contracting a circumscribed circle circumscribing the body region until the circle circumscribes the muscle region, based on the positional data determined for the abdominal wall muscle layer region in (c); a third extraction means which extracts a total body adipose region from the body region; a separation means which separates the total body adipose region into a visceral adipose region and a subcutaneous adipose region based on whether a specified region is located inside or outside of the line automatically set by the second extraction means to surround the abdominal wall muscle non-adipose layer region; and a display control means which controls display of the tomographic image on an image display device with clear indication of the visceral adipose region and the subcutaneous adipose region.