How Long Does it Take to Gain 20 Pounds of Muscle?

2026 Update: I’m not sure, but I think Jeremy Ethier may have called me out. In his latest video, currently at 1.7 million views, he claims that anyone saying it’s possible to gain 20 pounds of muscle in 3 months is being dishonest. If you google that claim, you’ll see my progress photos, some of my client’s progress photos, an AI summary that quotes me, and this article.

I see where the mistake comes from. It’s common mistake. What’s strange is that Jeremy Ethier disproves himself in his own video. I’ll go through it.

Gaining 20 pounds of muscle is a common goal for skinny beginners. If you’re starting off underweight, like I did, that will almost certainly be enough to bump you up to a healthy bodyweight. It’s enough muscle to look noticeably bigger and stronger, too. You’ll start picking up compliments from your friends and family members. It’s a big change.

Most skinny guys can gain 20 pounds within a few months. That’s long enough to build good habits and get some momentum going, but not so long that that it’s hard to keep up your motivation.

I’ve been helping skinny guys bulk up for 15 years. I’ll show you a ton of examples. You’ll see what it looks like on different guys, how lean their gains are, and how long it took them.

Introduction

It’s common for naturally thinner guys to assume they have bad muscle-building genetics. Nefarious terms get thrown around. We get labelled ectomorphs or hardgainers or skinny fat. There’s a grain of truth to those terms. If you click those links, we’ll explain the nuance.

But that isn’t how it works. Even if you have bad genetics, being skinny means you’re still quite far away from your genetic muscular potential. You’ll almost certainly be able to build muscle faster than the average person.

You can think of it like fat loss. Imagine a guy who weighs 400 pounds. He almost certainly has bad genetics for gaining fat, but he’s accumulated that fat in such excess that he’s in a position of being able to lose fat faster than the average man.

I know this sounds controversial, but it isn’t as controversial as it seems. There’s a clear trend. Thinner guys tend to be able to build muscle faster, at least at first. We see this trend in the research, all the top experts have noticed it, and we’ve seen it in our own clients, ranging from everyday desk workers all the way up to Olympic athletes.

First, we’ll cover what it takes to bulk properly, then how long it will take to gain 20 pounds.

Case Study: Obe’s 20-Pound Bulk

Obe’s Workout, Diet & Lifestyle Plan

Obe is a student studying commercial aviation. He’s married, naturally skinny, and spends his free time playing soccer and watching movies. A little over 5 weeks ago, he started the Bony to Beastly Program.

Here’s what he did to bulk up:

• He did three full-body workouts per week. Each workout took about an hour to complete. The workouts were specifically designed to stimulate muscle growth.
• He ate a nutritious bulking diet. We recommend eating healthy meals with a balanced mix of protein, carbs, healthy fats, fibre, and micronutrients. We gave Obe a recipe book full of recipes he could use. He was also free to eat other meals. We aren’t strict.
• His lifestyle was already quite healthy. We normally teach people how to improve their lifestyles and sleep. Obe was already doing great.
• He barely used any supplements. He had trouble eating enough protein, so he bought a tub of whey protein. Creatine would have been another wise choice, but Obe decided not to use it.
• He ate an ENORMOUS calorie surplus. He decided to bulk aggressively, eating in a large calorie surplus. He was gaining weight very fast, totally unafraid of gaining fat.

Obe’s Progress Photos & Measurements

When guys join the Bony to Beastly Program, we recommend taking before photos and measurements, then posting an introduction in the community. It’s optional, but it lets us say hi, answer questions, and adjust the program as needed. Here’s Obe’s introduction:

Whats up everyone! My name is Obe and I’m a student. I’ve always been skinny, so I’m freaking stoked to be part of this program. I’m 5’11 and currently weigh 135 pounds. The most I’ve ever weighed is 140. I hope to bulk up to 150-160 and be healthy as well as faster and stronger.

Obe

Here’s his before photo:

And here are his starting measurements:

• Weight: 134 pounds
• Biceps: 12 inches
• Shoulders: 41 inches
• Waist: 27.5 inches
• Thighs: 19.2 inches

Guys can update their progress whenever they want and ask as many questions as they like. The workout routine is organized into four phases, each lasting 5 weeks. After each of those 5-week phases, we recommend posting a full update, including new measurements and progress photos. That way we can see how things are going and offer advice. Here’s what Obe wrote:

Started week 5 today. I had to buy new pants. I can no longer stretch in them, even ripped a pair last week! I know it sounds dumb, but it’s a sick feeling! Below are my results. I couldn’t be more proud. I’ve started eating more greens. Specifically beets, avocados & spinach. I’m certain that had something to do with my waist staying lean.”

Obe

Here are some of his progress photos:

Here are his “after” measurements:

• Weight: 154 pounds (+20 pounds)
• Biceps: 13.8 inches (+1.8 inches)
• Shoulders: 46 inches (+5 inches)
• Waist: 32.5 inches (+5 inches: so much food in there!)
• Thighs: 22.4 inches (+3.2 inches)

Obe gained 4 pounds per week. It took him 5 weeks to gain 20 pounds. Obe’s waist circumference increased by quite a bit, but he didn’t gain a noticeable amount of fat. That’s quite rare when gaining weight this quickly. He did an amazing job. His results blew me away. I still haven’t fully coalesced.

We normally recommend gaining 20 pounds over 3–5 months. Obe did it in just 5 weeks.

What Does 20 Pounds of Muscle Look Like?

When guys talk about gaining 20 pounds of muscle, they’re speaking casually. If someone starts at 140 pounds at 11% body fat and bulks up to 160 at 13%, they’ve gained 15 pounds of lean mass and 5 pounds of fat. Much of that lean mass comes from extra contractile tissue, but some is from food in the digestive system, more glycogen in their muscles, denser bones, more blood vessels, and tougher tendons.

Still, when that guy looks in the mirror, he looks bigger. It looks like he’s gained 20 pounds of muscle, so he calls it muscle. When we’re talking about gaining 20 pounds, that’s what we’re talking about. Here’s what it looks like:

How Fast Can Skinny Guys Gain 20 Pounds?

If the average guy tried to gain four pounds per week, he’d gain quite a lot of fat. Even for skinny guys, gaining 4 pounds per week is incredibly fast. We usually recommend gaining between 0.5–1.5 pounds per week. Gaining more slowly tends to yield leaner gains, whereas gaining weight faster tends to yield faster muscle growth.

Some guys, especially if they’re starting out fairly lean and skinny, can gain weight quite fast without gaining a noticeable amount of fat. Here’s another example:

GK gained 1.4 pounds per week, allowing him to gain 20 pounds in a little over 3 months.

During my first bulk, it took me 2 months to gain 20 pounds. During my second bulk, it took me 3 months to gain another 20 pounds:

During my second bulk, I helped my skinny roommate bulk up. He followed the same workout and diet program as me. He gained over 20 pounds in the first month but slowed down afterward. After 4 months, he’d gained 27 pounds:

To see how quickly the typical skinny guy can build muscle, we went through 23 progress threads in our community (in order) and averaged out their results. For more examples, we’ve posted a bunch of before-and-after photos.

On average, most guys who followed our bulking program gained 25 pounds by the time they finished. It took the average guy 20–25 months to finish. That means they gained a little more than a pound per week.

Conclusion

The common rule of thumb is that it takes about a year for the average beginner to gain 20 pounds of muscle. That isn’t wrong, but it’s overly simplified. The average person is overweight, and most overweight people aren’t trying to bulk up. Most of them are trying to lose weight.

If you’re reading an article like this one, chances are you’re on the thinner side. Thinner guys are further away from their genetic muscular potential, so we tend to build muscle faster, especially at first. This early period of rapid growth is called “newbie gains.” We can speed that process up even more by bulking—by eating in a calorie surplus.

In our experience, the average skinny guy can gain 20 pounds in 20 weeks without gaining a noticeable amount of fat. But if you want to play it safe, you can gain weight more slowly. You can control how quickly you gain weight by adjusting how many calories you eat.

For more, we have a free bulking newsletter for naturally thin guys. If you want help bulking up, check out our Bony to Beastly Bulking Program. We’ll walk you through the entire process.