Trim (100-115 lbs) Transformation Guide: How Skinny Men Build Muscle

A man at 100 to 115 pounds builds muscle fastest by eating 2,800 to 3,200 calories a day, getting 100 to 120 grams of protein, and lifting full body four days a week with small weight increases every week or two. Expect about 2 to 4 pounds a month in the first few months if you hit your food.

The older version of this guide used a push/pull/legs split five days a week. I now start Trim clients on full body four days a week, because it trains each muscle more often with less total fatigue.

Who is the Trim archetype?

Men between 100 and 115 pounds, with an ectomorph or ecto-mesomorph build. Shapes are usually rectangle, pear or inverted triangle. You can build muscle, but you need more food than most guys to do it, and you burn through calories fast.

Most Trim men have tried “eating more” for a week and given up. Or they train six days a week, do cardio, and wonder why nothing changes.

Why aren’t you growing?

Three reasons, in this order.

You are not in a surplus. If the scale is not going up, you are not eating enough. Full stop.

You are not adding weight to the bar. Muscle grows when you do more over time. Same weights, same reps, same results.

You are doing too much. More sets past a certain point stop helping and start eating into recovery. Research shows more weekly volume builds more muscle up to a point (Schoenfeld et al., 2017), but you need to recover from it, and that takes food and sleep.

How many calories and how much protein?

• Calories: 2,800 to 3,200 a day, about 500 over maintenance
• Protein: 100 to 120 grams a day
• Carbs: high. Rice, oats, potatoes, bread, pasta, fruit

At 110 pounds, about 1.6 grams of protein per kilogram is around 80 grams, which research shows is roughly where the benefit for muscle gain levels off (Morton et al., 2018). The 100 to 120 gram target covers you. More protein than that fills you up and makes it harder to hit calories.

What does a week of training look like?

Four full body sessions on Monday, Tuesday, Thursday and Friday. About 60 minutes each.

Day A

• Barbell back squat: 3 sets of 8, rest 2 minutes
• Bench press: 3 sets of 8
• Barbell row: 3 sets of 10
• Hip thrust: 4 sets of 10, rest 90 seconds. Start with bodyweight or the empty 45 pound bar and add 10 pounds every 7 to 10 days.
• Biceps curl: 2 sets of 12

Day B

• Romanian deadlift: 3 sets of 10. Start at 65 to 95 pounds and add 5 to 10 pounds a week.
• Overhead press: 3 sets of 8
• Lat pulldown or assisted pull-up: 3 sets of 8 to 10
• Walking lunge: 2 sets of 10 per leg
• Triceps pushdown: 2 sets of 12

Alternate A and B. When you finish all sets at the top of the rep range with clean form, add weight next session. Keep cardio to walking.

What if you train at home?

Use a backpack loaded with books for hip thrusts and squats, push-ups with your feet on a chair, and bands or a doorway pull-up bar for rows and pulldowns. The rule stays the same: more load or more reps over time.

What should a normal day of eating look like?

• Breakfast: 1 cup oats cooked in whole milk, a banana, 2 tablespoons peanut butter, 3 eggs
• Lunch: 8 ounces chicken thighs, 2 cups rice, vegetables with olive oil
• Pre-workout: bagel with cream cheese, a glass of milk
• Dinner: 8 ounces ground beef, pasta, cheese, salad
• Before bed: Greek yogurt with granola

That is about 3,000 calories and 150 grams of protein. You can trim the protein a bit and add more rice if you are too full.

What should you expect at week 1, week 4 and week 12?

Week 1: You will feel full. Weight goes up 2 to 3 pounds from food and water.

Week 4: Squat, bench and row numbers are clearly up. You are 4 to 6 pounds heavier.

Week 12: Most Trim men gain 8 to 12 pounds. Chest and shoulders look wider. If you have gained less than 5 pounds, add 300 calories a day. If you gained more than 15 and your waist grew more than an inch or two, pull back 200.

Is this plan right for you?

Look at three things. Is the scale flat even though you think you eat a lot? Have you trained for months without adding weight to the bar? Do you want size without turning gym time into a second job? If yes, this plan is built for you.

Under 100 pounds, start with the Ghost guide. Once you pass 115, move to the Lean (115-135 lbs) guide. For more on gaining weight the right way, read the best way to put on weight.

What is the next step?

Take the XPL quiz, check coaching options and pricing, or read muscle building essentials.

Written by Zavier King, personal trainer in Houston and founder of XPL. ISSA Certified Personal Trainer and NASM Nutrition Coach. More about me.