Doctors often recommend low-protein diets for people with kidney disease because such a diet delays the worsening of kidney disease. However, patients who don't eat protein lose muscle. When patients lose enough muscle, they become weak and less able to carry out their usual activities. Lifting weights (resistance training) builds up muscle and reduces loss of muscle in such diseases as HIV infection and congestive heart failure. No one has tested resistance training to see if it prevents loss of muscle in patients with kidney disease who are following a low-protein diet.