How Long Does it Take to Gain 20 Pounds?

Gaining 20 pounds is a great goal for a beginner. It’s ambitious enough to produce dramatic results. You’ll be noticeably bigger, stronger, and more robust. You’ll push your clothes to their limits.

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 it becomes demotivational.

We have personal experience bulking up. Perhaps more importantly, we’ve helped over 10,000 other skinny guys bulk up over the past decade. We’ve averaged some client stats and got permission to share progress photos and measurements from one of their bulks.

A skinny guy bulking up and becoming muscular, illustrated by Shane Duquette.


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.

However, we’ve been doing this for over ten years, spoken with all the top experts, and worked with clients ranging from deskworkers to Olympic athletes. There’s a clear trend. Thinner guys tend to be able to build muscle faster, at least at first.

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.
Illustration of a skinny guy doing deadlifts to build a thicker back.

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.


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.”


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:

Before and after photo showing a skinny guy gaining 20 pounds of muscle.

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:

Before and after photo of a skinny guy bulking up and becoming muscular.

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:

Before and after progress photos showing Shane Duquette bulking up.

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:

Jared's before and after progress photos showing him going from being a skinny ectomorph to being muscular.

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.

Key Takeaway

Everyone is different, and everyone builds muscle at a different rate. The good news is that thinner guys are further away from their genetic muscular potential, so we tend to build muscle quite fast, especially at first. This early period of rapid growth is called “newbie gains.”

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.

Photo showing the Bony to Beastly Bulking Program for Skinny and Skinny-Fat Guys

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

Shane Duquette is the founder of Outlift, Bony to Beastly, and Bony to Bombshell, each with millions of readers. He's a Certified Conditioning Coach (CCC), has gained seventy pounds, and has over a decade of experience helping more than ten thousand naturally thin people build muscle. He also has a degree in fine arts, but those are inversely correlated with muscle growth.

Marco Walker-Ng is the founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell. He's a certified trainer (PTS) and nutrition coach (PN) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. He has over 15 years of experience helping people gain muscle and strength, with clients including college, professional, and Olympic athletes.