A back support device (100) having a first convex region (160) and a concave region (200) being connected to the first convex region (160), the first convex region (160) and the concave region (200) being configured to support respective regions of a users back, wherein a ratio between a straight line distance across the first convex region (160) and a straight line distance across the concave region (200) approximates a geometric progression.
