Cardio slows metabolism
When you first do cardiovascular activity, you breathe hard, your muscles burn, and the activity feels just plain difficult. But over time the exercise gets easier, and your only option from that point forward is to continuously do more and more cardio. This is your body adapting to the stress.
Second, cardio sends a signal to the body that says “become good at this activity”. Getting good at cardio means using less energy while doing it. Your body adapts by sparing calories and pares down on its primary calorie-burning tissue, muscle. (Why long distance runners have skinny stick-like legs with very little muscle. The hours of cardio make their body more efficient at saving calories, by slowing down their metabolism.
As a part of this adaptation, the metabolism rate slows down because metabolism boosting muscle is being sacrificed, marking fat loss harder.
Your body is undergoing metabolic adaptation, in which it slows down its calorie burn by reducing muscle mass.
With cardio, your body becomes very efficient at storing more calories and it becomes better at burning fewer calories. At the same time, you are losing muscle and muscle promotes a healthier metabolism.
Tons of cardio erodes muscle and slows down your metabolism, making long term fat loss very difficult.
When your metabolism slows down your body desperately holds onto fat.
Content : The resistance training revolution book
