I was told by my GP to expect periods of often intense back pain when the weight starts to come off . Apparently, our spines adjust to carry the extra weightload and to accommodate a different way of walking, that we all do as we get bigger and bigger. After losing weight, our spines have to adjust back again as there isn't as much pressure/weight on it. The problem is, most of us have put the weight on over a number of years, so our spines had more time to adjust. When we lose the weight after WLS, it is generally too quick for the spine to keep up when it needs to adjust to our new weight and our new way of walking, etc.