When you have a minute, can you offer a quick synopsis of the methods? Seems like a mess of confounding variables, primarily psych, would make this challenging (and has been the reason for long standing debate on the topic).
While somewhat encouraging, it seems to oppose earlier similar research on the topic which found no clear link.
The authors touch on prior studies and how there are conflicting results in regards to the relationship between LBP, obesity, and sex.
Sorry for the choppy summary below. As I don't have a right to distribute the study it feels wrong to post a bunch of information from it on a public form.
Methods
"Selection Criteria
"Studies were included in the meta-analysis if they fulfilled the following criteria: (1) cohort studies in which LBP incidence was an outcome; (2) clear definition of overweight and obesity as defined by the BMI in kg/m2; and (3) reported effect estimates of the relative risk, hazard ratio, or odds ratio (OR) with 95% confidence intervals (CI). Articles were excluded by the following criteria: (1) duplicate of previous publication; (2) reviews, comments, meeting abstracts, or other kinds of literature; and (3) case-control studies or cross-sectional studies.
"Assessment of Methodological Quality
"The Newcastle-Ottawa Scale was used to assess the quality of included studies.12 The Newcastle-Ottawa Scale is based on 3 major components: selection of the study groups (0–4 stars), comparability of cases and controls (0–2 stars), or cohorts, and ascertainment of exposure or outcome (0–3 stars). A study awarded Z6 stars is considered a high-quality study."
"Large number of participants from cohort studies, allowing a much greater possibility of reasonable conclusions."
"Incorporated a maximal bias adjustment in the pooled estimate; thus, the effect of potential confounders was minimized."
"Most included studies were adjusted for potential confounders." There is always the possibility of unaccounted for confounders.
I have not read the studies that the meta-analysis used. The authors did discuss how even when excluding groups of data based on confounding factors there was not a statistically significant change in the association with overweight and LBP. Adding credibility to the result. There was also stronger correlation between obesity and LBP than over weight and LBP, this remained consistent as well.
Of course correlation does not prove causation, but when combined with deductive reasoning it does provide an avenue worth pursuing in the absence of better information.
Similarly, this does not demonstrate that reducing BMI corrects LBP (which was not examined here). I feel weight loss is worth recommending, both because it could help with back pain through several mechanisms and for a multitude of other health reasons.