Anatomy, which is commonly thought of as the study of the human body, is a flawed concept to begin with.
Some people try to blame their pain on their obesity. In some cases this is true, but what I have seen in practice is that this is far less true than you would think. I recently had a lady patient who is over 400 lbs and she had low back pain that was excruciating especially when she worked since she was on her feet all day. She was worried that she would not be able to work and not be able to pay her rent and take care of herself. After a couple weeks of care, she was pain-free and has been pain-free for about 7 months without losing any weight.