The flank is the side of the torso between the bottom of your rib cage and the top of your hip bone on either side of your body. In simple terms, it’s that strip of your side where “love handles” or a “muffin top” can show, running from just under the ribs down to just above the pelvis. Doctors may also call this the lumbar or posterolateral abdominal region, and pain here is often labeled “flank pain.”