Should Skinny Guys Do High Or Low Reps To Build Mass?

Should skinny guys do high or low reps.

Choosing the best rep range to build muscle can be confusing. What works for a trained bodybuilder does not always work for an untrained beginner. This post explains whether skinny guys should do high or low reps to quickly put on mass

Skinny guys aiming to build muscle should do low reps rather than high reps. Lifting in a lower rep range allows heavier weights to be lifted. And lifting heavy weights is the most efficient way to increase muscular size and strength as a beginner.

Below, I explain why I think low reps are better for skinny beginners.

I started to build muscle and strength as a skinny guy when I switched from high reps light weight to low reps heavy weight.
I’m an ex-skinny guy who has experimented with both high and low-rep ranges.

Key Takeaways

  • High rep ranges are defined as 15+ repetitions per set.
  • Low rep ranges are defined as 6 repetitions or less per set.
  • High rep ranges are usually loaded with lighter weights and low rep ranges are usually loaded with heavier weights.
  • Skinny beginners can build muscle mass using both rep ranges but low reps are generally more efficient for growth.

Definition Of High Vs Low Reps

High reps are generally considered to be anything over 15 repetitions per set. This type of rep range is usually loaded with lighter weights.

In contrast, low reps are generally considered to be anything below 6 or 5 repetitions per set. This type of rep range is usually loaded with heavier weights.

Moderate rep ranges of 8-12 repetitions also exist. These are usually loaded with medium weights.

Heavy Vs Light Lifting: Which Is Better To Build Mass?

Why low reps high weight is better for skinny guys to build muscle vs high reps low weight.

To understand why it’s generally better for skinny people to lift low reps to build mass, it helps to first understand what happens to a muscle when you lift high vs low reps:

  • High-rep lifting using light weights- presents a strong time under tension (TUT) stimulus. This refers to the total duration your muscle remains contracted during a workout. Lighter weights allow you to lift more reps which increases TUT.
  • Low rep lifting using heavy weights- presents a strong mechanical tension stimulus. This refers to the amount of load a muscle is put under (i.e. weight lifted). Heavier weights result in greater mechanical tension but it also means fewer reps lifted.

Both stimuli are known to be drivers of hypertrophy (muscle growth).

But the latter is generally considered to be a stronger driver of hypertrophy for beginners.

High Reps Light Weight Benefits

The advantages of lifting higher reps and lighter weights for skinny guys to build mass:

  • Greater time under tension stimulus. This is great for getting a good “pump” (also known as the “swole” feeling) in the target muscle. TUT is also a strong driver for muscle hypertrophy.
  • Ideal for small isolation-type exercises. High-rep training can be used to build muscle as effectively as low-rep training for small exercises like bicep curls (if performed at a sufficient intensity)
  • Controlled form. Lifting lighter weights allows for better lifting form. This is beneficial for maximal muscle activation and provides a strong hypertrophy stimulus.
  • Increased peak contraction. Lifting lighter weights allows you to squeeze at the end of repetitions for the greatest peak contraction. This maximizes muscle activation.
  • Better mind-to-muscle contractions. This refers to how effectively your nervous system activates a target muscle. Using lighter weights allows you to focus on lifting through the range of motion, increasing your mind to muscle contractions, and thereby increasing your ability to lift heavier weights in the future.
  • Safer for beginners. Using light weights and high reps can be a safe and beginner-friendly way for you to start lifting weights and start making your first muscle gains as a skinny guy.

Low Reps Heavy Weight Benefits

The advantages of lifting lower reps and heavier weights for skinny guys to build mass:

  • Greater mechanical tension stimulus. Lifting heavy weights is the best way for skinny guys to get stronger and pack on muscle mass. Mechanical tension is widely known to be the strongest stimulus for driving muscle growth.
  • Increased strength progression. Lifting heavy weights for low reps is the most efficient way to progressive overload (increasing weight over time). Regular overloading is essential for making the quickest muscle gains.
  • Less cardiovascular demand. As a skinny guy with poor cardiovascular fitness, you may be limited on how much weight you can lift if you’re doing high reps. And this limits your ability to build mass. Using heavy weights and low reps minimizes this problem.
  • Shorter workouts. It’s essential to consider workout duration as a skinny guy. You want to keep your training to short but intense sessions to avoid overtraining and for the greatest muscle-building results. Lifting low reps with heavy weights is the best way to do this.

Can Skinny People Gain Muscle Size With High Reps?

The average skinny guy can build muscle using high reps. In fact, most forms of weight training can help a beginner to get bigger. However, high reps are not the most efficient way to muscle size for someone who is new to weight training.

When To Use High Reps To Build Muscle & Strength

The guys at Mind Pump recommend periodically transitioning to high reps as an effective way for trained lifters to introduce new hypertrophy (growth) stimuli to their muscles and promote size gains. This does not apply to skinny newbies though!

As a skinny beginner, you have one great thing going for you: newbie gains. This refers to the honeymoon period of rapid muscle growth that untrained lifters experience in response to most forms of weight training.

What are the implications of newb gains?

It means as a skinny beginner, you’ll generally find it easier to build muscle (assuming you follow a good training and diet plan).

In fact, you can actually gain muscle regardless of whether you’re lifting high reps using a lighter weight, or low reps using a heavier weight.

However, it’s important that your workouts are performed at a sufficient intensity.

If you’re new to weight training, you may be interested in my other post which explains how fast it takes a skinny guy to pack on mass.

Why Skinny Guys Should Not Do High Reps Low Weight

Skinny people should generally avoid doing high reps to build muscle. Lifting lighter weights for greater reps is not the most efficient way to promote muscular hypertrophy in beginners.

Low reps are better than high reps for building muscle and strength.

As a skinny guy looking to build muscle, you should know that “mechanical tension”- presented through lifting heavy weights for fewer reps- is the most potent and primary hypertrophy stimulus.

In contrast, TUT- presented through lifting light weights for more reps- is a secondary hypertrophy stimulus.

In other words; lifting heavy weights using low reps is how your muscles will grow the fastest.

So why do some bodybuilders and trained lifters sometimes transition to high-rep TUT lifting?

Mainly to give their muscles a new stimulus to adapt and grow to.

This is something skinny beginners do not have to do. And as a skinny guy, you should generally instead stick to the low-rep lifting using heavier weights!

If you’re new to working out, you may be interested in my other article on why beginners should lift heavy to build muscle.

Why Low Reps Heavy Weight Is Better For Skinny Guys

Low reps are better than high reps for skinny people who want to quickly build mass. Lifting in a low rep range allows for heavier weights to be loaded onto a muscle. This is one of the most effective ways for a beginner to promote muscle strength and size gains.

Low reps using a heavy weight is ideal for skinny guys to increase muscle size.

I can say that I’ve made most of the common lifting mistakes as an ex-skinny guy who struggled to build muscle.

And one tip that I preach to fellow skinny dudes is this:

You need to lift heavy and keep adding weight to get bigger!

Indeed, this was the primary reason I credit for my own skinny to muscular transformation.


As I mentioned previously, loading your muscles with heavy weights is the only way to present them with the mechanical tension stimulus required to drive rapid growth.

And the only way you’ll be able to lift heavy enough loads is by lifting in a low rep range.

Doing this is also the best way to quickly build strength.

And after you’ve built a foundation of strength, only then should you begin to experiment with higher rep ranges for the aforementioned TUT stimulus.

Recommended Rep Range For Beginners

So far I’ve established that skinny guys should avoid high reps and stick to low reps for maximal muscle growth.

However, different muscle groups also respond better to high vs low reps as follows:

Muscle GroupHigher Or Lower Reps Better?Recommended Rep Range For Skinny Guys
Biceps and tricepsHigher8-12

Generally speaking, the larger muscle groups and big compound movements respond better to lower reps and smaller muscles respond better to higher reps.

What About Sets?

As a beginner, 3-4 heavy workouts per week are ideal.

This allows you to reach the recommended 10-15 total sets per muscle per week, as well as rest each muscle for at least 24-48 hours between workouts to allow for repair and recovery.

To reach 10-15 total sets per week in 3-4 workouts, you should aim for 3-5 sets per muscle group per workout.

I would not recommend exceeding 6 sets per workout since this has been indicated by scientific studies to result in so-called wasted sets.

This refers to the diminished muscle-building benefits that occur after you exceed 6 sets per muscle per workout.


Skinny guys CAN build muscle using high reps and light weights if it is performed at a sufficient intensity to fatigue the target muscle.

However, lifting in high rep ranges is not the most efficient way to build muscle.

If you’re a beginner looking to get bigger fast, then you should consider using lower reps and heavier weights instead.

You may also be interested in the downloadable Kalibre Blueprint PDF which details exactly how I gained 40lbs of lean muscle (it’s 100% free!). It details the exact exercises and nutrition (with printables) I used to go from skinny to ripped!


I'm Kal (B.S, M.S)- a health & fitness writer and owner of Kalibre Fitness. I love to nerd out on weight training and nutrition. My primary interests are in muscle hypertrophy mechanisms and strength development. You can connect with me in the "Contact Us" section below!

Recent Posts