While investigating certain aspects of animal physiology, neurology or behavior, research scientists sometimes must limit the amount of food or water provided to animals used in a study. Such limitations can negatively impact the health and welfare of laboratory animals by, for example, causing them to experience distress or pain. The author discusses the veterinary and regulatory concerns that laboratory personnel should consider when limiting food or water given to research animals. He concludes that by adequately addressing the needs of animals receiving less food or water than required by regulation, researchers will improve both animal care and scientific study results.