The ornamental design for a back-saver belt-supported bag hook, as shown and described.
FIG. 1 is a perspective view of a back-saver belt-supported bag hook showing my new design, wherein the back-saver belt-supported bag hook is illustrated in use attached to the belt of a user to transmit the weight of the bag directly to the pelvis and legs thereby alleviating pressure on the spine, the dashed line showing is for illustrative purposes only and does not form a part of the claimed design;
FIG. 2 is a perspective view of the back-saver belt-supported bag hook;
FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror-image thereof;