For someone who is thin, building muscle mass can be very difficult without some professional help. Where for some fortunate genetically blessed people, gaining muscle mass very fast is a breeze. Therefore if you are trying to figure out how long does it take to build muscle mass, there is simply no straight forward answer.

Firstly, do take note that muscles do not usually grow in a linear process but in a series of spurts. Therefore no matter how hard you work your muscles or how much you eat, muscle growth will not be at a predictable steady pace.

That said, let's take a look at the factors which influence muscle growth. As you probably know, there are many factors influencing your muscle growth and not everyone will build muscles at the same pace even though they may be working out with the same weight, exercises and eating the same food.

Some people are genetically predisposed to gaining muscle mass and these folks will see impressive results within only a few months. We all know that the Mesomorphs (sporty body type) will be able to build muscles muuch faster than the Ectomorphs (thin body type).

Your rate of your muscle gain will also depend largely on how close you are to the upper limit of what you naturally are capable of in terms of gaining muscle mass. This phenomenon is also known as the adaptation ceiling in bodybuilding speak.

This gors to say that the closer you are to the upper limit of the adaptation ceiling, the slower your muscle will grow. That means that someone who has been lifting weights for a number of years will gain muscle mass much more slowly than a newbie to weight training.

It is not uncommon for people to gain fat when they are building muscle mass. The amount of fat you gain will depend on how much you eat and also on how lean you are when you started to fuel your muscle growth with what you eat. Eating to fuel muscle gain is called overfeeding in the bodybuilding lingo.

Studies have shown that during a period of overfeeding, you will gain more muscle and less fat if you are the naturally lean type. During the cutting phase to get rid of body fat so as to show muscle definition, it is known that fatter people tend to lose more fat and less muscle when they cut, but the leaner ones will find it the harder to lose fat without losing muscle.

Why is this so? Well, it may only be a psychological reason. If you have just worked your butt off to get your well defined six pack abs, then you will not want to put the fat on again and so you may simply be reluctant to eat the amount of food necessary to gain significant muscle mass, don't you think so?

It could also be hormonal factor as some studies do show a link between low body fat and low testosterone(male muscle buiding hormones) levels. If your testosterone is low, it is also difficult for you to gain muscle mass.

So how long does it take to build muscle mass will depend very much on your genetic condition and other factors besides doing the proper workouts and eating correctly.