In general the human small intestine, including the jejunum and ileum, this location is the main organ of the body to absorb nutrients. If a section of the small intestine is cut off, this will result in less area for the body to absorb nutrients, thus leading to malnutrition. It depends mainly on the reason for the surgery, if it is due to a serious disease or tumor in the intestine, this is unavoidable. If the surgery is not done, it may lead to a more serious situation. If there is no other reason, some people cut the small intestine to lose weight or for other reasons, it is not necessary.