If you are a skinny guy and have trouble building muscle, you are not alone. This article will provide you with a workout split that is engineered to add quality muscle mass to your frame, and include diet tips to enhance the process. 

Having a thin and lean physique with a small amount of muscle mass is known as having an ectomorphic body type.  Low amounts of body fat, but also a low amount of muscle mass. 

skinny guy transformation

Being an ectomorph comes with a certain set of challenges that can be overcome with the proper training protocol.  Since people with this body type tend to have a high metabolism, any food consumed is easily used for energy.

The benefit is that you will have low body fat levels, but gaining and maintaining muscle is a challenge.  I know this because I’ve been there.  When I started working out regularly, I weighed only 145 lbs.  Over the years I learned several principles and tactics that can save you a tremendous amount of time and energy and get you on the fast track to achieving your goals.

Pitfalls to Avoid 

To successfully make the transition to a more muscular physique, it is important to avoid common pitfalls.

Ectomorphs looking to gain size almost always resort to using a weight gainer shake.  The typical mindset is that by consuming the extra calories from the shake, you will gain weight and it will be mostly muscle.  This couldn’t be further from the truth.

There is nothing wrong with supplements, or weight gainers specifically, but mixing some sugar and fat laden powder into a shake, and downing it three times a day will do nothing for you but make you gain fat.

Since your goal is to build lean muscle, it is important to avoid any quick fixes.  There are no quick fixes in fitness. 

Another common mistake with muscle building plans or “bulk cycles” is that people tend to use it as an excuse to eat whatever they want.  This will inevitably result in fat gain, and not the lean muscular physique you originally sought after.

Instead of eating pizza and ice cream every day, eat healthy carbs and lean protein.  Simply increase the amount to reach a higher caloric intake.


With a healthy diet throughout the week, a cheat day once per week is also beneficial when gaining mass.  It will give you some extra calories to provide you energy for your workouts, help boost your metabolism, and give you a much needed break from a clean diet.

A final pitfall to steer clear of in your quest to gain muscle is to lift extremely heavy.  It is well known that increased resistance will result in an increase in muscle hypertrophy.  However, that only applies when good form is used.

Using more weight than you can handle will likely result in injury due to poor form.  It is crucial to get a full range of motion, and to feel the muscle contracting with each repetition.

Muscle gain occurs when the actin and myosin fibers of the muscle are broken down, and after proper rest and nutrition repair themselves and grow.

Therefore, use moderate to heavy weight, but only use weight that you can complete the recommended number of reps with good form.

The single most important thing that someone with an ectormorphic body-type can learn about gaining muscle is to make gradual changes to their physique.

In today’s society, everyone is looking for a quick fix.  With infomercials touting the latest “get fit quick” trends, and media outlets with photoshopped images of perfect bodies, people’s view of getting fit is warped.

The truth is that making solid gains to your physique will take time, discipline and dedication.  The good news?  If you put in consistent, dedicated effort, the results you get will be lasting.

The Skinny Guy Muscle-Building Workout Split 

The split below has been designed to make it possible for you to increase lean muscle mass in your physique.

Since the goal is muscle gain, each day will focus on a single muscle group.  This way, you will be able to give each part an equal and adequate amount of training.  This will also allow for ample recovery time so you can avoid overtraining.

The order of muscle groups in the split is not arbitrary—it is specifically planned so each body part is fresh the day you train.

For example, if I put a biceps workout the day after a back workout, your biceps session would suffer due to being already trained the day before.  This split avoids any such overlapping.

This program also focuses on larger muscle groups in the beginning of the week when you are fully rested, then tapers down to the smaller ones later in the week.

In each session, begin with a few heavier compound moves.

For example, a legs workout may begin with barbell squats, then dumbbell lunges.  For the compound exercises, keep the range between 6-10 reps and complete three to four sets.

After the compound exercises, transition to a few single-joint exercises to exhaust the muscles in a more direct and targeted fashion.

In this legs workout example, the next exercises may be lying leg curls, followed by leg extensions, and finish with seated calf raises.  In the isolation exercises, three sets of 8-12 reps per exercise is sufficient.

There are two off days per week that allow for full recovery.  Abdominal workouts should be done three times per week, and moderate intensity cardio should be done one to two times per week.

Your New Workout Split

Monday Chest

Tuesday Back

Wednesday Legs

Thursday OFF

Friday Delts

Saturday Arms

Sunday OFF

While on this muscle building program, your diet should consist of lean meats, fish, fruits, vegetables, and complex carbohydrates such as oatmeal, sweet potatoes, and whole grain bread.

Make sure that directly after your workout you have fast acting, simple carbohydrates and a fast acting whey protein shake with a small amount of sugar.

After a few weeks on this plan, you can switch to full body workouts, performed three times per week so your body doesn’t adapt to the training.  Then after one to two weeks of the full body exercises, you can switch back to the muscle building split.

Skinny Guy Muscle-Building Full-Body Workout Routine

BB Deadlift  12, 10, 8, 6 [Increase weight each set]

Walking Dumbbell Lunge 3 sets of 10-15 reps per leg

T- Pushup 3 sets of 12 reps

Standing BB Press 3 sets of 8-10 reps

Bench Dips 3 sets of 15-20 reps

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Close-Grip Chin-ups 3 sets of 10-12 reps (can use machine or band for assistance if needed)

Renegade Row 3 sets of 8 reps per side 

Hanging Leg Raises  3 sets of 20 reps

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Swiss Ball Pass 3 sets of 20 reps

Thanks for reading!  Post in the comments if you have any questions, comments, or challenges building muscle.  I’d love to hear from you!