A recent study in Spine Journal looked at about a thousand twins in Spain:
They compared different measures of obesity (BMI, fat percentage; waist circumference and waist-hip ratio) and did not see that the heavier twin was any more predisposed to have chronic back pain. It is very common to have patients who blame themselves for having pain, and they often ask if their weight is to blame. Some have even said that their doctors have told them that's why they have back pain, which is literally adding insult to injury. While there are habits that may help your back, blaming your size is not one of them. Bad pain happens to good people, sometimes with no reason why it decided to start. There's not always a smoking gun to say why it will happen. Olympic athletes and professional dancers will also suffer from back pain, and it's not because they need to lose weight. As a chiropractor and physical therapy provider, I will do an exam to find the root cause of your pain and work with you to alleviate it as quickly as possible. Call or email if you have any questions.