Everyone has a unique body odor (BO), which can be pleasant or faint, but when we think of body odor, we often think of an unpleasant smell. Changes in body odor can be caused by puberty, excessive sweating, or poor hygiene. Sudden changes are often triggered by the environment, medications, or the food you eat. However, body odor, especially sudden and persistent changes to your normal scent, can sometimes be a sign of an underlying health condition.