Scientist: Laboratory animals have access to ample food, and they get relatively little exercise  These factors can skew the results of research using animals, since such studies often rely on the assumption that the animal subjects are healthy
For instance, animal studies that purport to show that extreme caloric restriction can extend lifespans take for granted that their subjects were not overfed to begin with
Some animal studies take into consideration the differences between the living conditions of laboratory animals and those of other animals.