Illustration showing a skinny guy who gained too much fat while bulking.

How Much Fat Should You Gain While Bulking?

One of the best ways to ruin a bulk is to be so scared of gaining fat that you avoid gaining weight. If you’re 130 pounds, the only way to get up to 180 pounds is to gain weight. There’s no other path there. You have to bulk.

But bulking is a dastardly process. You can just as easily mess it up by gaining too much weight, causing you to gain a disproportionate amount of fat. You can cut the fat away, of course. It still works out in the end. But cutting takes time, and feeling fat can be frustrating.

To make things even trickier, there are a number of factors that can affect the ratio of muscle-to-fat that you gain, including your workout program, your bulking diet, your genetics, and even your sleep habits. It’s possible to bulk at a reasonable pace and still gain a ton of fat.

That brings us to the big question: how much fat should you gain while bulking? And if you notice your body-fat percentage going up, does that mean you’re doing something wrong?

Illustration of a skinny guy bulking up, gaining far more muscle than fat.

Focus on Gaining Muscle

The whole point of bulking is to gain muscle size and strength. If some fat comes along for the ride, that’s not ideal, but it’s okay. It’s fairly easy to get rid of any fat you gain, especially if you’re naturally thin, and especially if there isn’t that much of it. Most guys have gone on a dreamer bulk at some point in their lives. I certainly have. I don’t recommend it, but it’s not the end of the world.

Where most skinny guys mess up is being so afraid of gaining fat that they fail to gain an appreciable amount of muscle. If you’re like me, starting off at 130 pounds at a height of 6’2, then the best path forward is to do a bonafide bulk, focusing on gaining weight, getting stronger, and getting bigger. It’s during those focused bulks that I made virtually all of my progress.

Before and after photos showing Shane Duquette bulking up leanly.

If you notice a bit of fat gain, that’s okay. The important thing is that you’re gaining tons of muscle. That’s how you’ll get big and strong. The trick is to make sure you aren’t gaining fat needlessly, that your fat gain isn’t disproportional, and that you never get so fat that it begins to harm your health (or appearance).

Before and after photo of a skinny guy leanly building muscle and bulking up in one year

For instance, Hugo spent a few months bulking up, focused on getting bigger and stronger. He gained a bit of fat while doing it, so he spent a couple of months cutting. By the end of the year, he was up 40 pounds and looked leaner than when he started. This is the power of bulking. It allows for fast muscle gain.

In fact, during my most disastrous dreamer bulk, where I stupidly gained around 25 pounds of fat, I also broke all of my personal strength records and built muscle that I’ve kept ever since. The only price I paid for it was having to spend 3 months cutting. Do I recommend it? No. But is it something to be afraid of? Definitely not.

If you focus on steadily gaining weight, and if you’re gaining strength in the gym every week on most of your big compound lifts, then your bulk is going okay. You’re making progress.

Gaining Fat Doesn’t Mean Being Fat

Just because you’re gaining fat while bulking doesn’t mean that you’ll become fat. If you’re a lean guy now, gaining another 5–10 pounds of fat won’t make you chubby. You’ll still be lean. You’ll just be a little bit less lean. And it will still look good and be healthy. There’s no real harm to it.

Before and after photo showing the results of a skinny guy bulking up with the Bony to Beastly Program.

For example, Dan bulked up extremely aggressively and gained a mix of both muscle and fat. You can see both the muscle gains and fat gains quite clearly. With that said, even after gaining some fat, he still looks great, and he’s still within the healthy body-fat percentage range. And the benefit, of course, is that he gained a ton of muscle.

The trouble is when people go on dramatic dreamer bulks and actually become fat. If you start off skinny-fat and gain 20–30 pounds of fat, you’ll become overweight. You may not like how you look as much. It may harm your health. That’s not what we’re talking about. We’re talking about gaining mostly muscle, a bit of fat, and staying within a healthy and attractive body-fat percentage range.

Also keep in mind that if you’re already unhappy with your body-fat percentage, there’s nothing stopping you from beginning with a cut. Many people are able to gain a bit of muscle while cutting, especially if they aren’t very muscular yet, and especially if they have higher body-fat percentages.

A before and after photo showing Johnny's cutting results.

For example, Johnny joined our program because he wanted to gain muscle. That’s our specialty. But he was unhappy with his body-fat percentage, so he started with a cut. By the end of the cut, he looked way more muscular.

What Ratio of Muscle to Fat Should You Gain?

Most beginners can gain muscle without eating in a calorie surplus. They can gain muscle while losing fat. Maybe they’re even losing weight while doing it. That’s because most people are overweight, and when they start lifting weights, they aren’t bulking. They’re dipping into their fat reserves for energy while using the protein they’re eating to construct muscle.

For skinny beginners, though, things change. We can’t build a significant amount of muscle without gaining a significant amount of weight. And with that weight gain, there’s the risk of gaining fat. That’s the risk we take while bulking.

Graph showing muscle growth and fat loss while bulking on a high-carb diet.

Now, even with bonafide bulks, there’s plenty of research showing totally lean gains. For instance, this study found that guys eating a good bulking diet while following a rigorous hypertrophy training routine were, on average, able to gain 7.5 pounds of muscle in eight weeks while losing fat. Some of our members are able to get results like that, too:

GK's lean bulking results

But when you’re driving your body into new territory, building muscle that was never there before, you’ll probably gain at least a little bit of fat. This is especially true if you’re an intermediate lifter and you’ve already gotten your newbie gains. Most studies, even when a good diet is combined with a good workout program, find that most people gain at least a little bit of fat while bulking. There’s nothing wrong with that.

Diagram showing that lean bulking reduces fat gain at the cost of reducing muscle growth.

With that said, there are plenty of factors that affect how much fat you gain while bulking. For example, in a study by Ribeiro et al., groups of intermediate lifters were put on a bulking program and instructed to gain weight at different rates. The group gaining two pounds per week built twice as much muscle as the group gaining one pound per week. However, they also gained six times as much fat.

If we look at the proportion of muscle-to-fat gain, the group gaining one pound per week gained 80% muscle and 20% fat. That fat gain would be very hard to notice. That’s a very lean bulk. The group gaining two pounds per week gained 60% muscle and 40% fat. That fat gain would eventually become noticeable, but they’re also gaining muscle at a ridiculous pace. Many guys would be thrilled with that.

For more, we have an article on how fast to gain weight while bulking and another on how to do a lean bulk.


As a general rule of thumb, if you’ve still got room on your frame for a significant amount of muscle growth, at least half of the weight you gain while bulking should be muscle. If you can do even better than that, gaining more like 80% muscle and 20% fat, sweet—that’s amazing.

Illustration showing the Bony to Beastly Bulking Program

If you want a full bulking program, including a 5-month workout routine, diet guide, recipe book, and coaching, check out our Bony to Beastly (men’s) program or Bony to Bombshell (women’s) program. Or if you want an intermediate bulking routine, check out our Outlift Intermediate Bulking Program. If you liked this article, you’ll love our full programs.

Shane Duquette is the co-founder and creative lead of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's personally gained sixty pounds at 11% body fat and has nine years of experience helping over ten thousand skinny people bulk up.

Marco Walker-Ng is the co-founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell, and is a certified trainer (PTS) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. His specialty is helping people build muscle to improve their strength and general health, with clients including college, professional, and Olympic athletes.

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