A study published on December 12, 2015, in the journal Chiropractic & Manual Therapies showed that being overweight or underweight does not have a significant effect on the outcome of various lower back pain treatments. However, being obese did have a negative impact on the results of care. The study begins by reporting that nearly 30% of the world population reports suffering from back pain while 80% report back pain at some point in their lifetime.
In this study, 681 people with lower back pain were included. Data was collected from each of the participants about their history of back pain, demographics, occupation history, disability, health status and mental health status. The participants were enrolled into one of four treatment protocols: medical care only, medical care with physical therapy, chiropractic care only, or chiropractic care with the use of physical modalities.
The participants were all treated according to the protocol of the doctor they were assigned to, using one of the four types of care categories. Outcomes of care were measured at 2 weeks, 4 weeks, 6 weeks, and 6 months after the initial treatment. For the purposes of this study, a comparison of the various types of care was not made to see if one type of care was more effective than another. Only the effects of weight as measured by body mass index (BMI) were evaluated to see if it had an effect on the results of whatever type of care the person was receiving.
The results showed that, across all treatment protocols, people who were considered to be obese had a decreased chance of improvement with their lower back pain. This included all times of follow-up as well as all levels of pain. However, being overweight, but not considered obese, did not have a significant effect on the outcome of care for any of the categories of care. Similarly, those who were underweight also did not show any significant decrease in their percentage of recovery.
The study did show that those who were obese and lost weight during care did have a better chance at recovery, and those who gained weight during care reduced their chance even further. All other groups of people showed no statistical difference in their ability to recover based upon their weight, unless they were considered to be obese.
In their discussion the authors wrote, Results of this study suggest that BMI is a relevant predictor of response to treatment. Obese participants are less likely to show improvement from LBP treatment regardless of the care they receive. They also stated in their conclusion, An association between obesity and less favorable treatment outcomes was inferred in this study. There appears to be an association between obesity and disability as well as obesity and subjective most severe pain.