Cardio is an aerobic exercise that reduces body fat as well as muscle mass. When one loses muscle mass their natural Basal Metabolic rate slows down which mean less calories are burned per day. Your lean body mass is directly correlated with how many calories you use up each day and how lean you can ultimately become. When you perform cardio daily your body will adapt to reserve as much energy as possible so the only thing to do is to add more cardio right? Wrong! As your body adapts to reserve calories it downgrades or slows down your metabolism. If you like to run for hours on end here is the energy – adaption response to cardio: The body over time will adapt and becomes more fuel efficient. It will learn to burn the fewest amount of calories possible in an attempt to be successful (success being run farther and longer all on fewer calories). With long distance running, fat is the major source of energy so your body will become extremely good on figuring out how to be great at storing and holding onto body fat. Now if you stop you may say “Hey, wouldn’t I be burning less calories per day and should gain fat?” The answer is no, your body will have already downgraded your metabolism so its burning fewer calories per day then you think. The only way to get your metabolism back is to feed your body and cut cardio out until you get your baseline diet in order. Once in order, you can manipulate foods to help you lose weight and implement an effective training schedule that will add lean muscle to your body. The more muscle you have on your body the more metabolically active your body becomes which means more calories are burned per day. The only way to achieve more lean muscle on your body is to incorporate hard resistant weight training. Weight training upgrades or speeds up your metabolism. The more muscle you add to your body the more permanent your metabolism stays upgraded. Having more muscle on your body is an adaption to weight training as the muscles realize they need bigger, stronger, and more of the fibers to compensate which will eventually lead to more muscle on your body. In layman terms the more lean muscle you have on your body, the more calories your body burns by doing nothing! Now take into account that you are expending energy (calories) during weight training, your body uses calories to help the muscle recovery from the workout (basically its cost the body energy to repair itself), and finally in GLUCOSE METABOLISM. Vincent Russo, 25 years old from Kenilworth NJ. Has a BA in Biology from Fairleigh Dickinson University in Madison NJ. A Bodybuilding.com Team Athlete, Silver Model, High School Football Coach, Teacher, Waiter/bartender. Was a top 5 finalist out of 500 guys for bodybuilding.com‘s 2012 BodySpace Spokes Model. Compete in the Men’s Physique category where in recent competitions placed 2nd in NPC East Coasts (Nov. 2011), and 3rd in Bodybuilding.com‘s BodySpace Spokes model competition (LA Fit Expo 2012).