Catabolic and anabolic are two different states that describe whether the body is building tissue or breaking it down. When you're trying to gain weight, you want to maximize the time your body is in a building state so that you can get bigger, stronger and see improvements in your performance. The way you eat, train and rest can affect the rate at which you'll see these improvements.
A catabolic state means that your body is breaking down tissue. Whenever you workout, whether it's cardio or weightlifting, you're causing tiny tears in your muscle. The longer and harder you workout, the more damage you'll cause to your muscle tissue.
An anabolic state means that your body is building or repairing tissue. When you rest, your body goes into damaged muscle tissue and begins repairing it. It's during rest, not exercise that you actually put on all of your size.
There are a few ways you can remain in an anabolic state for the maximum amount of time thereby helping you to put on more size. Proper nutrition is very important. Eat meals that contain protein every 2-3 hours.
When you don't eat for a long period of time, your body can start breaking down muscle tissue for energy (catabolic state). The best way to prevent this is to eat often, including the morning.
Never skip breakfast. When you wake up, you haven't eaten for 8-10 hours and your body is basically starving. You need to give it some nutrients quickly in order to get out of the catabolic state you're probably in.
Your workout sessions also shouldn't last longer than about 90 minutes. The longer you workout, the more tissue your body will breakdown. If your workouts are longer than 60 minutes, consider using a sports drink such as Gatorade or Powerade to help power your way through it.
The Bottom Line
Remember that if you're trying to gain weight, you need to let your body rest. Working out too much will actually make you smaller because your body won't have an adequate amount of time to rebuild and repair damaged muscle tissue. Avoid working out the same muscle group more than once every 72 hours.