Before you learn exactly how your body builds or maintains muscle by doing weights, you must understand one principle:

Your body likes to stay in a state of equilibrium. It likes to be comfortable. And when it is pushed out of its comfort zone, it changes so that it won't have to adapt as quickly next time it faces the same challenge.

This is exactly what happens when you lift weights with an intensity that really pushes your muscle to the edge. Your body is totally out of its comfort zone. Once it is out of its comfort zone, your body reacts by transforming itself so that it will be able to bear a similiar load more comfortably next time.

This is a lot like your body developing a callous during heavy manual labor with your bare hands. As you are doing the work, there is a strain put on the skin of your hands. Your body adapts by easing the irritation by making the skin thicker. That thicker skin that forms is what we call a callous. And no matter if we think it looks ugly or whatever, it's just your body protecting yourself against an external stimulus that causes it irritation.

Well, as we've said weight lifting is an intense irritation. And your body reacts by adapting through 3 stages:

Neural Adaptation - This occurs when the strain from lifting the weight brings to life all the muscle fibers existing in the muscle as it stands right now. You see, muscle fibers in a particular muscle have to work in tandem to contract the whole muscle. And a feature your muscle fibers have is that have an all or nothing response. They either contract or they don't, they don't contract halfway like your arm might. So the bigger the strain, the more fibers are recruited to help lift the weight. Before your body feels a strong enough weight to force it to grow, it has to go through this phase first. You have to make sure you use everything you've currently got in your muscles, before it is forced to grow.

By only reaching neural adaptation you strengthen the current muscle, but you don't grow it.

Hypertrophy - This is the next stage, where the goal is solely to build the muscle size. At this point all of the existing muscle fibers have been recruited and you are pushing your muscle to the point of failure. The existing muscle fibers are all contracted and your body is calling for more fibers to contract, but can't find them. At this stage you reach muscular failure. This is what you want to achieve when you are trying to lose weight. Although you won't be gaining massive size due to the calorie deficit of your eating plan, by pushing your muscles to the point of failure you'll at least maintain your muscle mass - and get the most muscle for the nutrients you are taking in.

At this point your glycogen stores are all out, and lactic acid starts to build up. This results in a burning sensation in the target muscle.

Endurance - This occurs after an hour of intense exercise. At this point you won't be getting increases in either size or strength, as your body turns into endurance mode. You can't accelerate, and so you can't achieve maximum muscle stimulus. Your muscles are just getting by, but not growing.

You want to avoid going anywhere near this point. This will not help you anywhere near as much as reaching the hypertrophy stage. Your goal with weight training is to get in the gym, train as hard as you can and leave when you've done enough to maintain your current muscles.

So how does reaching the hypertrophy adaptation phase help muscle maintenance or growth?

Well, as we've said, when you reach hypertrophy, all of your muscles fibers have been employed to lift the weights. If you push your muscle to failure (until the point when you cannot perform another repetition of the muscle with the correct technique), then your muscle has been totally exhausted. You experience thousands of micro-tears in the muscle under that intensity.

And that's the state you leave the gym. You've pretty much overloaded your muscles, and you can imagine that they are wrecked.

So that's a common myth debunked. Most people think your muscles grow in the gym. That's not the case at all. Your muscles are 'shattered' after an intense workout. All the growth occurs during your rest time, which is why your resting time is just as important as your workouts.

So what sort of exercise program can you get on, that will help reach hypertrophy, and have an overall exercise plan to support fast weight loss?

I recommend two programs.

Tom Venuto's "Burn The Fat" ebook is the first recommendation because apart from containing a great section on exercise (he's a natural bodybuilder and personal trainer), he also has the best overall book on weight loss - from the many I've reviewed.

If you're only interested in the exercise section, then I believe Craig Ballantyne's "Turbulence Training" is best for you. His nutrition package may not be as comprehensive as Tom's book, but his exercise section is just killer. It is the best one I've seen that's targeted for weight loss. He even covers bodyweight exercises in his course (which is using your own bodyweight to simulate weight training without the weights).