How Fast Can You Gain Weight?

When beginning a weight gain program, almost everyone asks themselves the following questions at some point in time:

“How much weight can I gain?” and  How fast can I gain weight?“.

Like most questions relating to bodybuilding, there is no simple answer to these two questions.  In order to answer these questions,  you first must learn which factors are responsible for the amount, and speed at which you gain weight.

How Much Weight Can I Expect to Gain?

The amount of lean bodyweight you can expect to gain is determined by three factors.

Those three factors are:

1)  Genetics

2)  Body type

3)  Hormone levels

Keep in mind that we’re not taking your weight training program and diet into account here, and both of these play a crucial role in the success of your weight gain program.  For the sake of this article, we will assume that you have designed a sound bodybuilding diet, and weight lifting program.

Now, let’s take a closer look at each of the factors mentioned above.


Your genetics are what determined the proportion of the different types of muscle fibers in your body (explained more thoroughly in the weight training section).   The distribution of the different fiber types will play a role in how much mas you can gain, as well as the speed at which you can build this mass.

The two types of muscle fibers in your body are:

  • Fast twitch (type II) fibers
  • Slow twitch (type I) fibers

The type II fast-twitch muscle fibers generate power and increase in size much more readily than the slow-twitch “endurance” fibers.

This means that if you were genetically predisposed with a high percentage of fast-twitch muscle fibers, for example, your body will respond very favorably to a weight training program, and you will likely be able to gain weight quickly and easily.fibers

If, on the other hand, you were born with a higher percentage of slow-twitch muscle fibers, gaining weight will be more challenging.  Now don’t get discouraged, I said more challenging, not impossible! Check out Trevor Reed’s muscle transformation for proof.

The bad news is that you can’t increase the number of fast-twitch muscle fibers in your body, meaning that you will have to work with whatever you’ve got.

The good news is that everyone has both types of fibers, and even if you have a higher percentage of slow-twitch fibers, you can still build plenty of muscle.   It just takes a little more work!

Body Type

Your natural body type also plays a role in the amount of lean body mass you can gain.  There are three body types (somatotypes) that most people fall into, and your body type will play a role in the amount and speed at which you can gain weight.

The three body types are:

  • Ectomorphs – Thin and lean with long limbs and narrow shoulders and hips.  Ectomorphs are usually referred to as hard gainers, since building muscle is particularly challenging for this body type.  The advantage of an ectomorph body type is the fact that body fat is rarely an issue.
  • Mesomorphs – Muscular, athletic build, with wide shoulders and narrow hips.  Everyone trying to build muscle hopes that they fall into this category, since a mesomorph body type can build muscle with ease, and will generally maintain low levels of body fat.
  • Endomorphs – Stocky, rounded build with wide hips and shoulders.  Endomorphs can usually build muscle relatively easily. However, they can also accumulate excess body fat with ease.

Some people fit one of these body type profiles perfectly, while most of us are a combination of two, with one being predominant.

So what does all of this mean?  In a nutshell, it means that if your primary body type falls into the ectomorph category, building muscle will be challenging. Still, you will likely stay lean, making your muscle very visible.  If you are primarily a mesomorph (the envy of many people!), you should be able to build significant amounts of muscle without much difficulty.  If you are an endomorph, you will build muscle with relative ease, but may also be plagued with increased levels of body fat.

Hormone Levels

The amount of certain anabolic hormones in your body will affect how much weight you can gain. Simply put, people with higher levels of hormones such as testosterone and HGH will build muscle faster than those with lower levels.   This is the reason why women can’t naturally build as much muscle mass as men.

Many different factors determine the levels of anabolic hormones in your body including:

  • Age
  • Overall health
  • diet and sleeping habits
  • Training regimen
Fortunately, you have control over most of these factors and can do your best to create an environment that promotes optimal levels of all of the anabolic hormones.

How Fast Can I Expect to Gain Weight?

First off, let’s just clarify that we are talking about lean body weight here, and not fat or water weight.  Most people should realistically expect to gain between .5 – 1 pound weekly.  Of course, there are exceptions, but these are very realistic numbers.

Mass gains are usually faster at the beginning of your weight gain program.  In the first year of your program, Huge gains of up to 40 pounds or more are possible.  In many cases, you’ll find that your gains are staggered as you reach plateaus and then break through them.

For example, you may go an entire 8-week stretch where you only gain two pounds of muscle, then all of a sudden you break through that plateau and build 5 pounds over the next three weeks.

After the initial rapid weight gain, expect to gain about 0.25 – 1% of your body weight per week.

So if we use a 150-pound man as an example,  realistic weekly muscle gains would be in the range of .37 – 1.5 lbs after the initial rapid increase in weight.  Any more than this, and you will likely be adding body fat.

This is assuming that you are training, eating, and supplementing effectively of course!

Putting it All Together

Assuming that you are following a sound muscle building program, the actual amount of weight you can gain depends on your genetics, body type, and hormone levels.  Most people can expect to gain between about .5 – 1 pound of muscle per week.

Regardless of your genetics, your body type, or your level of hormones, you have to constantly experiment with your diet and training program to find out what triggers muscle growth for your body.

Don’t be discouraged if you’ve had trouble gaining weight in the past, or think that your genetics won’t allow you to gain mass.  With a little hard work and smart program design, even hard gainers can achieve outstanding results.