How Many Calories Should a Skinny Guy Eat to Build Muscle?

Struggling to gain size as a skinny guy? Learn how many calories you need to eat to build muscle, with a simple calculation that actually works.

If you’re naturally skinny, building muscle comes down to one thing:

You need to be eating in a consistent calorie surplus. Not just for a day or two, but for weeks.

Here’s how to work it out step by step.

Step 1: Multiply Your Bodyweight by 33–38

Use this formula to estimate how many calories you should eat daily:

Bodyweight (kg) × 33–38 = Daily Calories

• Start with 33 if you’re brand new to training.

• Use 36–38 if you’re already lifting and not seeing the scale move.

📌 Example:

If you weigh 65kg and you’re not gaining weight at 33×, try bumping up to 36–38×.

65 × 36 = 2,340 kcal per day

This is just a starting point. If you’re not gaining after 2 weeks, add 100–150 kcal and re-check.

Step 2: Prioritise Protein 🍗

Muscle is made from protein. Without enough of it, the extra calories you eat can turn into fat instead of size.

📌 Use this:

Bodyweight (kg) × 2g = Daily protein target

Example:

65kg × 2

= 130g of protein per day

Eat a source of protein in every meal - meat, eggs, protein powder, Greek yogurt, etc. And track it.

Step 3: Be Consistent for Weeks, Not Days 📆

Muscle takes time to build. Most skinny guys fail because they give up after 1–2 weeks of “eating more” without tracking anything.

You should be:

✅ Hitting your calorie and protein targets daily

✅ Tracking your weight weekly (not daily)

✅ Sticking to the same training program for at least 4–6 weeks

What If You’re Still Not Gaining?

Here are 3 quick fixes if the scale won’t budge:

1. Add a liquid meal - like a smoothie or shake; easier to digest. 🥤

2. Increase portion sizes slightly - instead of adding extra meals.

3. Double-check your tracking - are you really eating as much as you think?

Muscle Gain Is a Process. But It Works.

If you’re frustrated by how slow it feels to gain weight, just remember:

Eat slightly more than your body needs.

Train consistently.

Let time do the work. ⏳

Most skinny guys fail because they give up too early, jump between programs, or don’t track what’s working. Don’t make the same mistake.

Want Personalised Help?

I coach naturally skinny guys who want to gain size without turning into a blob. If you’re tired of guessing your calories, tracking aimlessly, and not seeing results…

✅ I’ll calculate exactly what you need

✅ Build a plan that fits your lifestyle

✅ And coach you through every step of the process

Contact me with any questions, otherwise feel free to book in a no obligation 30-minute consultation below.

👉 https://www.bealdbodies.com/contact-alex