Feet shrink for a variety of reasons, including significant weight loss and disease. Neuropathic joint disease sometimes causes foot bones to disintegrate due to nerve damage. Scleroderma, a rheumatolgical condition, sometimes causes toe bones to shorten due to bone loss.
Unless a considerable amount of weight is lost, foot length generally remains the same. However, a reduction of up to 1 1/2 shoe sizes is not unusual due to an overall reduction in the circumference of the foot. Neuropathic joint disease is most commonly associated with diabetes, although syphilis is another possible cause. The effects of both neuropathic joint disease and scleroderma are manageable, but they are not reversible.