Excess weight increases the weight on the discs and small joints in the lower back. Increased weight increases compression, degeneration, and pain. Also, excess weight is not gained symmetrically, and as a rule, most weight gain is at the abdomen.  This creates a “lever arm” that multiplies the actual load (weight) on the discs and small joints of the lower back. The lower back muscles must then contract to maintain an upright posture, further adding to the weight pulling on the spine.