By the way some guys train and eat, you’d swear they were trying to lose muscle, not build it. But, hey, maybe that’s what they want—and if you want to join them, you’re more than welcome to. So if you’re looking to lose some size—if you’re already so jacked that your biceps are tearing your sleeves, and your dream is to look skinny and weak—you can do what they do. Or maybe you’re doing it already and don’t even realize it.
The only way to find out for sure is by checking out our list of the 10 worst workout mistakes—things you do that sabotage your progress and cost you muscle. Recognize a mistake as part of your daily routine? We also came up with some quick and easy fixes you can use to correct these problems and net truly awesome gains.
There are three ways that cardio typically cancels out muscle gains: doing it too often, doing it for too long, or doing it on an empty stomach. In general, daily cardio sessions simply burn too many cumulative calories to allow you the surplus you need for muscle mass, and the same can be said for sessions that last 45 minutes or more.
Work out in the morning before breakfast and you only compound the problem. When you wake up, your body is already in a catabolic (muscle-burning) state, since a night’s sleep—time spent without eating—empties your tank. Working out immediately just reinforces this condition and costs you intensity—whether on the treadmill or with the weights. The end result: You burn muscle as fuel in place of calories you should have consumed at breakfast.