Joint pain is one of the first and most noticeable health problems caused by being overweight
Your joints have it tough. Even at your target weight, they are still under near constant pressure to facilitate movement without giving in or giving out. But when you surpass your target weight, the burden can become unbearable. Take your spinal joints for example: those in the lumbar are responsible for bearing and stabilizing the weight of your upper body while still allowing for a modicum of movement. Piling more and more weight on top of these joints means reduces their capacity to provide this function, while also causing them to degrade.
Your spine is built for stability but it still has to move
If it was so rigid as to not move, it would simply crack from the shearing forces that we put it through on a daily basis. Therefore, it is ingeniously constructed so as to provide stability but still retain a level of independent movement. This is enabled by the functional spinal unit, also known as the spinal motion segment, or the articular triad.