Ingrid Heuch, M.D., Ph.D., from Oslo University Hospital in Norway, and colleagues analyzed data from the community-based HUNT 2 (1995 to1997) and HUNT 3 (2006 to 2008) studies of an entire Norwegian county, including 8,733 men and 10,149 women aged 30 to 69 years, who did not have chronic LBP at baseline, and 2,669 men and 3,899 women with LBP at baseline. Groups were assessed for chronic LBP after 11 years.The researchers observed a significant positive association between BMI and risk of LBP among persons without LBP at baseline. For BMI of 30 kg/m² or more versus BMI less than 25 kg/m², the odds ratio for chronic LBP was 1.34 for men and 1.22 for women, when adjusting for other factors, including age, education, work status, physical activity at work and in leisure time, smoking, blood pressure, and serum lipid levels. BMI and recurrence of LBP among women were also significantly positively associated. There was negligible influence from LBP status at baseline on subsequent change in BMI.