48 Hour Rule
Every exercise routine should include rest days, just make sure that you only take one at a time. A study at the University of Missouri-Columbia found that after two consecutive days off their running wheels, rats began to show an increase in belly fat. If squeezing in a full workout the day after your dayoff seems unlikely, even just a few minutes of cardio, such as climbing stairs or walking can make a difference.
Fitness Magazine July 2007