Many people know, an increase in weight can lead to an increase in back pain.  Part of that is from shifiting in posture as well as actual pressure in the joints of the spine potentially leading to more osteoarthritis/degeneration.  According to a study done in 2008, an interesting thing occured: as the study’s patients’ BMI (body mass index) levels dropped, disc spaces between the vertebrae in the lumbar spine expanded. This in turn opened up the space nerves have, which decreased pressure on pinched nerves, and over time, could reduce pain.

Reference

 Djurasovic M, Bratcher KR, Glassman S, et a. The Effect of Obesity on Clinical Outcomes After Lumbar Fusion. Spine 2008; 33(16): 1789-1792