How Fast Should You Gain Weight While Bulking?
I remember being skinny and wanting to gain weight FAST. I didn’t just want to be muscular yesterday, I wanted to be muscular in every single one of my previous lives.
We aren’t just trying to gain weight, though; we’re trying to gain muscle. And if we bulk up too fast, won’t we become skinny fat? That can happen. Not to everyone, but it can happen to some of us. Sometimes. It’s important to understand the risk factors.
Over the past eight years, we’ve helped nearly 10,000 skinny guys bulk up quickly, leanly, and everything in between. Even when dealing with naturally skinny guys, there’s no one-size-fits-all approach.
Let’s discuss the pros and cons of gaining muscle quickly versus gaining it leanly. That way, you’ll know exactly how much weight you should be trying to gain on the scale each week.
- The Tortoise and the Hare
- Why is a Big Calorie Surplus so Effective?
- How to Know if You Should Bulk Fast
- How Quickly Can a Skinny Beginner Build Muscle?
- How Fast Can Intermediates Build Muscle?
- Will Gaining Weight Fast Make Us Fat?
- How to Build Muscle Fast
- How to Make Lean Gains
- How Much Weight Should You Gain Per Week?
- How Much Weight Should You Gain Per Month?
- Summary
The Tortoise and the Hare
Do Slow & Steady Gains Win the Race?
A new study looked into how different rates of weight gain affected muscle growth and fat gain. Does gaining weight faster yield extra muscle growth? Will gaining weight slower make our gains leaner? This study answers those questions.
Now for the fun part. This study was reviewed in Monthly Applications in Strength Sport (MASS) by Eric Helms, PhD. The title of his review was: When Gaining Muscle, the Tortoise Beats the Hare.
Is that true?
So, first of all, as you probably know, there’s this old Aesop’s Fable about a tortoise and a hare. I’m sure you’ve heard it before. The story goes something like this:
- Once upon a time, a hare mocked a tortoise. “You’re so slow! How do you even get anywhere?”
- The tortoise wasn’t fazed. “I get places faster than you might think. I bet I could even beat you in a race!”
- The hare laughed. What a joke! “Alright, let’s race.”
- When the race began, the hare bounded out of sight, leaving the tortoise plodding in his dust. So far, so good. But the hare soon tired and took a nap.
- The tortoise paced himself. He marched slowly, yes, but he marched steadily. And while the hare napped, the tortoise overtook him, winning the race.
The moral of the story, of course, is that slow and steady wins the race. Persistence outperforms speed.
But what if the hare took a shorter nap? Or what if the tortoise was a little bit slower? Or what if the hare raced to the finish line and then took his nap?
With a story like this, the details make all the difference.
How Slow Are Lean Gains?
Okay, now let’s talk about the new bulking study. The researchers took intermediate natural bodybuilders and split them into two groups.
- The tortoise group ate a modest calorie surplus and gained 1 pound per week on the scale. After 4 weeks, they had gained 2.6 pounds of muscle and 0.7 pounds of fat.
- The hare group ate a massive calorie surplus and gained 2 pounds per week on the scale. After 4 weeks, they had gained 5.3 pounds of muscle and 4 pounds of fat.
Quick note: when Dr. Helms reviewed this study, he noticed that the researchers used a poor way of calculating muscle and fat gains. So I’m using the corrected results from the MASS review, not the study itself.
Anyway, it’s easy to see why Helms favoured the tortoises. By eating in a smaller calorie surplus, they were able to gain muscle three times as leanly:
Does that mean that the tortoises won the race, though? I guess that depends on what the race is. Are you racing to get bigger, to build muscle, or to avoid fat gain?
If you’re just trying to get bigger, gaining weight more quickly is the fastest way to do it. You’ll gain a mix of muscle and fat, making you look much bigger and buffer.
If this is a race to gain lean mass, bulking faster is still better. The hares gained lean mass twice as fast:
This is an impressive amount of lean mass, too. These intermediate natural bodybuilders are gaining over a pound of lean mass every week. They’re gaining fat, too, yes, but that’s a fearsome rate of muscle growth.
The catch is, not all lean mass is muscle growth. Even fat gains contain some lean mass. We can’t say that these bodybuilders were gaining 1.3 pounds of muscle every week. However, most of the lean mass we gain tends to be muscle.
Is Bulking/Cutting Faster than Lean Bulking?
That brings us back to the story of the tortoise and the hare. Remember, the hare didn’t lose the race because he was slower; he lost the race because he had to take a break in the middle.
If we’re talking about bulking, the hares may need a break to cut off the extra fat they gained. We need to factor that break in.
- The tortoise group gained 0.7 pounds of fat.
- The hare group gained 4 pounds of fat.
Keep in mind that the hare group also gained more lean mass. The extra fat will be spread thinner over much larger muscles. And besides, going up a couple of body-fat percentage points might not even matter. It may even help.
For example, if someone is going from 9% up to 14%, the extra fat will make them look bigger in clothes, giving them a fuller face and a thicker neck. That will make most guys look noticeably stronger and healthier:
Not only that, but moving up into a healthier body-fat percentage can give us more testosterone, less cortisol, a stronger immune system, and more energy (study, study, study, study).
But for the sake of simplicity, let’s say that the hare group wants to lose that extra 3.3 pounds of fat.
Losing such a small amount of fat can be fast, especially for skinny guys like us. If we cut hard, we could lose it in a single week. That’s extreme, though. Let’s be generous. Let’s say it takes the hares three weeks to lose that extra fat. After all, we’re talking about how much fat we can lose while napping.
During these three weeks, the tortoises are still plodding along. They’re still gaining 0.7 pounds of lean mass per week. Will they catch the hares?
The next thing we need to do is determine our finish line. I dig twenty-pound bulks. That’s usually enough to turn a skinny guy into a fit guy or a fit guy into a strong guy:
So let’s say the goal is to gain twenty pounds of muscle.
Now we can plot out our race:
- The tortoises gain 0.65 pounds of muscle every week, so it takes them 31 weeks to gain 20 pounds of muscle.
- The hares gain 1.33 pounds of muscle every week but need a 3-week break every four weeks. That brings their rate of muscle growth down to 0.76 pounds per week. At that rate, it takes them 26 weeks to gain 20 pounds of muscle.
In this case, the hares beat the tortoises by a whopping five weeks.
Was the Tortoise Even Bulking Slowly?
My favourite thing about this study is the surprise plot twist. Even the tortoises were bulking hard. I mean, if you do some googling about how much weight intermediate lifters should gain per week, here’s what you’ll find:
- Eric Helms from MASS: 0.5–1.5% of body weight gained per month. For a 150-pound guy, that’s 0.2–0.5 pounds per week.
- Andy Morgan from Ripped Body: 1–2% of body weight gained per month. That’s 0.3–0.7 pounds per week.
- Steve Kamb from Nerd Fitness: 2 pounds gained per month. That’s a little under 0.5 pounds per week.
There’s only one exception to the rule:
- Mike Matthews (Legion Athletics): Aim to gain 0.5–1 pound per week.
As you can see, Mike Matthews has the most aggressive recommendation. And even then, the supposed tortoise is bulking at the upper limit of that range.
The tortoise isn’t a tortoise. He’s gaining weight at twice the speed that most people recommend, and he’s making lean gains while he does it.
Looking closer, the tortoise is just a hare in disguise. He shaved his whiskers, painted himself green, tied his ears around his neck, and hid inside a turtle shell. I mean, scroll up and look at that thing. He’s a hare.
Anyway, here’s what happens if we add the typical rate of weight gain to the graph:
The “tortoise” gaining a pound of muscle per week is an argument for bulking fast. It shows that even while gaining a full pound per week, we may be able to make lean gains.
Now, don’t get me wrong, some guys do benefit from bulking more slowly. And other guys may benefit from bulking faster. I think that anywhere from 0.5–2 pounds per week can make sense.
But a pound per week is a good default. And a pound per week is fast.
Why is a Big Calorie Surplus so Effective?
The thing with gaining weight slowly is that your hormones will be fairly average. That’s not bad by any means by any means. But it’s not ideal, either.
By gearing into a larger calorie surplus, you’ll gain a few important advantages:
- Constant nutrient influx allows us to build muscle all day long.
- More testosterone and insulin improve our ability to build muscle.
- More glycogen packed into our muscles improves workout performance and muscle growth.
- Activation of mTOR allows us to construct more muscle.
- More weight gain promotes muscle growth.
In the words of Mike Israetel, Ph.D.:
All else being equal, eating more is the most powerful tool for muscle gain, as long as you’re training hard.
–Mike Israetel, PhD
How to Know if You Should Bulk Fast
We’ve seen that bulking very fast is great for gaining tremendous amounts of muscle. We’ve also seen that bulking moderately fast is great for gaining muscle leanly. Both approaches involve rapidly gaining weight, and both approaches can work wonders.
But there’s more than just this one bulking study to consider. Dr. Helms points to this older study, where the hare group was eating 600 calories more per day than the tortoise group, which proved to be too much. They gained slightly more muscle but twice as much fat.
What’s interesting is that the hares were only gaining about a pound per week. That’s not even all that fast, yet most of their gains were fat. So it’s clear that in some circumstances, it’s better to gain weight more slowly.
On the other hand, we also have plenty of research showing rapid rates of muscle gain:
- This study found that beginners were able to gain 9 pounds of muscle during their first eight weeks of working out.
- In this study, another group of beginners was able to gain an average of 12 pounds of muscle during their first ten weeks of working out.
- In another study, beginners were able to gain 15 pounds of muscle during their first 12 weeks of lifting weights.
In all of these studies, the body composition changes were incredible. In one of them, they even lost fat while gaining more than a pound of muscle per week. This means that there are situations where it pays to gain weight more quickly.
Reasons to Gain Weight Slowly
- Strength training: Strength training is great for gaining strength, not building muscle. If you’re doing a strength training program, you’ll want to gain weight more slowly.
- Upper-body emphasis: Over half of your muscle mass is in your lower body. Your quads are your biggest muscles, then your glutes, then calves, then hamstrings. If you aren’t squatting and deadlifting hard, you’ll want to gain more slowly.
- Fatphobia: if the idea of gaining some fat scares you, you may as well play it safe and bulk more slowly.
- Higher body-fat percentage: if you’re pushing 15% body fat, gaining more fat might harm your appearance. If you’re already pushing 20%, gaining more fat could hurt your health, especially if your waist circumference is encroaching on forty inches.
However, even if you’re following a good bulking program, you may still want to bulk more slowly. We’ve had some clients do great with slower bulks. Here’s a sweet progress update from Mikey:
He’s halfway through our bulking program and has been gaining an average of 0.5 pounds per week. I can’t imagine a bulk going better than this. Super lean gains.
Reasons to Gain Weight Quickly
- You’re skinny: the skinnier you are, the more quickly you can build muscle.
- You’re a beginner: if you’re new to lifting weights, your muscles will respond very well.
- You’re naturally lean: if you’re naturally lean, chances are that you have fewer fat cells. You’ll be less likely to gain fat, and even if you do, it will melt off afterwards.
- You’re a hardgainer: if you’re a skinny guy who just can’t gain weight, try being more aggressive. Your body will naturally fight off the fat gains anyway. It’s good at that.
- Hypertrophy training: workouts designed specifically for muscle growth will stimulate more muscle growth. (Obviously.)
- High-carb diet: if your diet is high in carbs (as opposed to fat) then you’ll be able to gain muscle more quickly and leanly.
- Great sleep: if you get a good 8 hours of sleep every night, you’ll be able to build muscle faster and leaner.
- High g-flux: if you have an active lifestyle, you’ll resist fat gain. Doing cardio and spending more time on your feet will allow you to bulk the most aggressively of all.
I’ve always bulked fast. During every one of my bulks, I’ve aimed to gain at least a pound per week. Then, to mitigate fat gain, I tried to optimize my training, diet, and lifestyle.
As a beginner, my gains were lean. As an intermediate, some fat came along for the ride. In either case, I would bulk fast and then rest hard. That’s how I gained 55 pounds in two years:
Over those two years, I bulked hard for 11 months and took things easy for 13 months. That means that while I was bulking, I gained 1.25 pounds per week on average.
We’ve used this approach with about half of our clients, too. Here’s Hugo’s one-year bulking transformation:
I’ll admit a bias. As much as I hate identity politics, let’s be real, hares have a thinner body type. They’re ectomorphs. As Seth Godin would say, they’re part of our tribe. Tortoises are shorter and rounder, and I’m sure they’re very nice, but they’re endomorphs. They’re that pesky body type who keeps out-benching us. I don’t like it.
But despite my bias, I think the facts bear me out. In fact, in situations like ours, even Dr Helms agrees:
Thus, large surplus gaining diets (among natural lifters) should probably be relegated to novice stages and only among relatively lean lifters who can afford to gain some body fat in the process.
–Eric Helms, PhD
After helping nearly 10,000 skinny people bulk up, we’ve come to the same conclusion. Aggressive bulking works best for skinny beginners.
How Quickly Can a Skinny Beginner Build Muscle?
When someone starts bulking, they go through a period of rapid muscle growth. This phenomenon is called newbie gains. As the weeks go by, these newbie gains fade. With every inch we add to our biceps, it becomes harder to add another. This is the law of diminishing returns. If you plotted out a beginner’s muscle growth, it would look like this:
However, we aren’t just beginners, we’re skinny beginners. We’re even further away from our genetic potential than the average man. As a result, the effect compounds:
Here’s our article about how big and strong you can get as a skinny guy. Your potential is probably greater than you think. But the point is, if you’re still skinny, chances are that you can build muscle incredibly quickly.
Aggressive Bulking for Beginners
Many skinny beginners can gain upwards of two pounds per week without visible fat gain. Not everyone can do it, and results here vary wildly, but we see it quite often.
If you look at our client transformations, you’ll see that plenty of guys can gain more than a pound per week without any noticeable fat gain, especially during their first 5–10 weeks of bulking.
In fact, Jared himself gained over twenty pounds during his first month of bulking without any visible fat gain. I had never seen anything like it. Since then, we’ve seen a handful of other guys do the same. Given how rare that is, we don’t recommend it. But it happens sometimes.
Here’s another cool example of lean gains while bulking fast:
You shouldn’t expect those exact same results. Everyone is different. This is just to say that as skinny beginners bulking for the first time, we’re in a great position to gain muscle fast.
In our experience, guys starting off lean and underweight (with a BMI under 18) sometimes benefit from gaining 1–2 pounds per week. Then, when they’re no longer underweight, we recommend slowing it down to 0.5–1 pound per week.
Lean Bulking for Beginners
Most naturally skinny guys can build muscle quickly and leanly. Gaining weight more slowly isn’t leaner bulking; it’s just slower.
However, not all skinny guys are naturally lean. We aren’t all starting our bulks at 12% body fat. That can change things. If you’re starting at 15% and you bulk up to 20%, you’re going to start looking out of shape. You won’t be able to see the muscle that you’re building:
That can be hard on some skinny guys. They’re fed up with being small and weak, so they dive into an aggressive bulk. But because they have a higher body-fat percentage, it only makes them even more skinny-fat.
If you’re already up over 15% and feeling a bit soft, it’s often better to shoot for slow and steady lean gains. You won’t build muscle as fast, but you’ll be able to bulk for longer, and you may even lose some fat while doing it. That way, your transformation looks more like this:
If you’re already pushing 20% body fat, we’ve got a different protocol for you. Here’s our article for skinny-fat guys.
Even for naturally lean guys, though, aggressive bulking will eventually lead to fat gains. Once you move beyond that beginner stage, your ratio of muscle-to-fat gains will drop.
And besides, beginners mess up sometimes. So far, we’ve been talking about how beginners can bulk up incredibly fast. And they can. But to get exceptional results, you need to be bulking correctly. Most beginners don’t bulk correctly.
- Beginners don’t always have the wisdom to choose the best hypertrophy programs. It’s common for beginners to take a DIY approach to building muscle. They read a few blog posts and combine bulking methods. That can work if you know what you’re doing… but beginners don’t know what they’re doing.
- Sometimes beginners don’t use hypertrophy programs at all. For example, they may try to bulk with a strength training program, such as StrongLifts 5×5. I don’t have anything against StrongLifts, but at its heart, it’s a strength program, not a muscle-building program. Strength training programs aren’t the same thing as hypertrophy programs.
- Beginners don’t always understand bulking diets. For example, many beginners reduce their carb intake as they gear into their first bulks. That’s not the way. You’ll build muscle more leanly by eating more carbs.
- Beginners don’t always know how to bulk aggressively. Bulking fast isn’t about training six days per week and taking every set to failure. That won’t speed up muscle growth, it will just harm recovery. Nor is it about eating a dirty (or clean) bulking diet.
In fact, it’s so common for beginners to mess up that there’s a term for it: dreamer bulking. It describes a naive bulker who thinks he’s building tons of muscle but is mostly gaining fat.
I don’t mean that in a mean way. Most skinny guys have at least one dreamer bulk before they smarten up. I’ve done it twice, so I’m certainly not above it. I don’t even regret it.
Most former skinny guys consider these dreamer bulks a rite of passage. We gain a bunch of muscle, a ton of strength, and, yes, a ton of fat—but we learn from it. Losing our abs for a couple of months isn’t anything to fear. It may even be worthwhile in the long run.
There are other ways to learn those lessons, though. One approach would be to learn those lessons from others. But if you favour a more DIY approach, that’s cool. I’ve been there. That’s a reason to bulk a bit slower. That way your mistakes won’t manifest themselves quite as flabbily.
If you’re still learning how to drive, no need to practice at 100 mph.
How Fast Can Intermediates Build Muscle?
If you’re a skinny beginner, most experts—myself included—recommend aggressive bulking. Our bodies are so primed for muscle growth that we can push our limits without much downside.
This period of rapid growth might last a few months. Maybe even a couple of years. Then you’ll hit a wall. Upping the calories will just raise your body-fat percentage higher. At that point, aggressive bulking becomes more controversial.
Once you’re an intermediate lifter, experts like Dr. Helms recommend slowing down. They recommend aiming for leaner gains over a longer period of time. This is when he recommends becoming the turtle.
How Fast Should Intermediates Gain Weight?
Let’s plot out an intermediate aggressive bulking example. Let’s say you’re starting your bulk at 180 pounds and 12% body fat, and you’re trying to gain twenty pounds. Let’s say that you’re gaining a pound per week. And because you’re already close to your genetic potential, you’re gaining 50% muscle and 50% fat.
Start of bulk:
- 180 pounds
- 158.4 pounds of lean mass
- 21.6 pounds of fat
- 12% body fat
End of aggressive bulk:
- 200 pounds
- 168.4 pounds of lean mass
- 31.6 pounds of fat
- 15.8% body fat
Results:
- +10 pounds of muscle
- +10 pounds of fat
- +3.8% body fat
Now let’s plot out an intermediate lean bulking example. You’re still starting at 180 pounds and 12% body fat, but you’re gaining 0.25 pounds per week. Since you’re gaining slower, your gains should be much leaner. Let’s say you gain 80% muscle and 20% fat.
End of lean bulk:
- 185 pounds
- 162.4 pounds of lean mass
- 22.6 pounds of fat
- 12.2% body fat
Results:
- +4 pounds of muscle
- +1 pound of fat
- +0.2% body fat
If we imagine how these results might look, we might get something like this:
Which Results Would You Prefer?
Both approaches would keep you healthy. In either case, you’re well under 20% body fat. And in either case, the quality of your training, diet, and lifestyle might be identical. No issue there.
But the lean gains guy would have better muscle definition and would be able to keep bulking. The aggressive bulker would be much bigger and stronger, but he may need a break.
They’ll have different challenges while bulking, too:
- The lean bulk requires a great deal of precision. It might mean calorie counting, at least for a while. They’ll need that precise 100-calorie surplus every single day.
- The aggressive bulk requires eating more calories. You wouldn’t need to be as exact. 300 or 700 extra calories. Both will result in tons of muscle growth. But eating those 300–700 extra calories every day is no joke. You may wind up feeling perma-full.
If you’re happy with your appearance and want to make gradual improvements, maybe lean gains are for you. Maybe you’d rather be a tortoise. Keep in mind that you need to be precise and that it may take a long time for your results to show.
If you want to build muscle fast and a little fat doesn’t scare you, you’ll prefer a more aggressive approach. You’re a hare. Just keep in mind that you may need to take breaks to cut when your body-fat percentage drifts too high.
Will Gaining Weight Fast Make Us Fat?
The worry that a lot of skinny guys have is that bulking fast will make them fat. There’s a bit of a misconception here. There’s a difference between getting fatter and getting fat. It all depends on how lean you’re starting.
You aren’t fat if you start bulking at 10% body fat and finish at 15%. You’re still well within the healthiest and most attractive body-fat percentage range. You may even look better at 15% body fat. Your neck and face will look fuller, and you’ll look buffer in clothes.
However, some skinny guys get attached to looking ripped. If you prefer being at 10% body fat year-round, I get that. Having striations in your shoulders looks cool. There’s nothing wrong with taking it slow simply because you want to.
How to Build Muscle Fast
We have the “lean and eager” approach for skinny beginners who want to bulk up fast. For them, we recommend gaining 1–2 pounds per week for the first few weeks, then one pound per week after that. That adds up to around 30 pounds over the course of our 5-month bulking program.
We don’t recommend bulking much past 15–20% body fat. That way, even if guys gain fat, they won’t harm their health or appearance. The only thing they’re risking by bulking more quickly is needing to take a break sooner than anticipated.
Bulking fast is fairly simple and doesn’t require much precision. You probably won’t need to count calories, and if you mess up here and there, it might not harm your results. It’s the approach I’ve always taken.
However, it can be hard to eat enough calories to gain weight quickly. Some skinny guys will prefer to gain weight slower simply because it’s easier on their digestive system.
How to Make Lean Gains
We also have the “soft and cautious” approach for guys who want to make lean gains. We recommend that they gain about 0.5 pounds per week during the program.
This approach requires more precision. We recommend tracking calories and aiming for a high degree of consistency. It’s more finicky. But you won’t feel as full, there’s a lower risk of gaining fat, and every day you’ll wake up looking a little bit better.
So in the end, how quickly should you gain weight while bulking? A skinny beginner who’s lean and eager to build muscle should gain 1–2 pounds per week. Everyone else should gain 0.5–1 pound per week.
How Much Weight Should You Gain Per Week?
If you’re trying to bulk quickly, you should gain 0.5–1 pound per week. If you’re a skinny beginner, you might want to gain as much as 1–2 pounds per week.
If you’re trying to bulk leanly, you should gain 0.25–0.5 pounds per week. If you’re overweight, skinny-fat, or having difficulty keeping your gains lean, you can gain weight even more slowly.
How Much Weight Should You Gain Per Month?
If you’re trying to take a longer-term approach to building muscle, you don’t need to focus on gaining weight every week. Instead, focus on progressively overload your lifts in the gym. If you start struggling to gain strength, you can start weighing yourself every month, seeing if your weight is trending upwards. If it isn’t, consider eating a little bit more food. That extra food will help you gain strength and muscle again.
Summary
Most skinny beginners can benefit from gaining weight quite quickly when they first start bulking. The extra nutrients open the floodgates of muscle growth, allowing us to build muscle much faster. Yes, gaining weight increases the risk of gaining fat, but with a good bulking program, that fat gain may not even be noticeable.
We usually recommend that skinny guys gain around 1 pound per week while they’re skinny and then switch to gaining 0.5–1 pound per week once they’re at healthier body weight.
We usually recommend that skinny-fat guys gain weight more slowly, gaining closer to 0.5 pounds per week. That way, they build muscle more leanly.
Alright, that’s it for now. If you want more muscle-building information, we have a free muscle-building newsletter. If you want a full workout and diet program, including a 5-month customizable full-body workout routine, a diet guide, a recipe book, and online coaching, check out our Bony to Beastly Program. Or, if you want a customizable intermediate muscle-building program, check out our Outlift Program.
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.
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When referring to the older study Dr Helms mentions, what would you say explains such a difference in the fat gained?
As it seems odd that between gaining roughly 0.5 (assumed from the study’s abstract?) pound per week vs 1 pound per week you double the fat gain without any significant increase in muscle, but between gaining 1 pound per week vs 2 pounds per week you suddenly gain more than double the muscle mass.
Hey Lee, that’s a good question. Usually, researchers try to control as many variables as they can within any given study. With these bulking studies, that often means giving them a specific workout program, having them take every set to failure, and giving them some dietary guidelines. In the more expensive studies, sometimes the workouts are supervised, and sometimes the meals are provided for the participants.
In the newer study, the participants were natural bodybuilders who were put on a hypertrophy program, all of their training was supervised, and they were given a specific diet plan. That’s a pretty good setup for producing a bunch of muscle growth. And this particular diet plan was super high in carbs, too. The tortoise group got 65% of their calories from carbs, the hare group got 75%. High-carb diets like this seem to work very well for aggressive bulks.
The older study was done on elite athletes who were put on a dedicated hypertrophy program, and the researchers supervised one workout per week. In this study, one group was told to eat for muscle growth but wasn’t given much detail as to how. Their appetite limited their calorie intake, and so they gained weight quite slowly. The other group was put on a specific high-calorie diet plan. That high-calorie diet plan, like the new study, was quite high in carbs, moderate in protein, lower in fat. Maybe a bit lower in protein and higher in fat, though.
In both cases, the hypertrophy programs looked solid. And in both cases, they were eating traditional bulking diets. Lots of carbs, eating fairly often, and hitting minimum protein targets.
One thing of note is that the bodybuilders focused all of their training on muscle growth, whereas the athletes were doing just as much sports-specific training as hypertrophy training. I’m not sure if that played a role. Some sort of interference effect, perhaps. That doesn’t normally happen to such a large degree, but these are elite athletes, so maybe they pushed the athletic training harder.
To be honest, I’m not sure what produced such different results. I mean, even within these studies, you have some participants faring far better than others. I tried to put the relevant factors in the article. I think by running through that list of factors, you’ll get an idea of how quickly you should be gaining weight. It’s not perfect, though. One of the most important things while bulking is to track your results and adjust accordingly.
Hmm, yeah maybe the athletic training did have some effect. Yeah I guess tracking and adjusting as you go along is the best way to do it.
You also mentioned that a reason to bulk more slowly is if you’re doing a program that emphasises the upper body. So, how much weight gain per week would you recommend for someone who has completed your main b2B program and is doing a specialist one e.g. War Chest or 8th Wonder.
Yeah, exactly. Those programs go easier on the squats and deadlifts, so I’d take a slower pace with them. We recommend gaining 0.5–1 pound per week with those programs, and if you’re trying to keep your gains as lean as possible, then err on the lower side of that.
I know this depends but how much extra muscle would you assume can be gained when gaining 1 pound per week vs 0.5 pound per week?
I ask because similar to what you mentioned above, the hare bulking aggressively then cutting was actually better off than the tortoise bulking 1 pound per week.
Also I meant specifically within the context of completing those specialist programs after the main b2B program.
If you’re doing everything right and you aren’t scared by the idea of gaining a bit of fat, I think you can bulk more aggressively and then cut as needed. Then, assuming you track what happens, that’s more data that we can take into account during your next bulk 🙂
Personally, I always try to gain a good pound per week while bulking.
Sounds good. Thanks for the great advice as always!
Hey Shane! I’d consider myself a beginner with most of my muscle potential still left on the table. I work long hours for 3 days of the week and cannot work out these days. These days are consecutive (Saturday/Sunday/Monday). That leaves me 4 days of the week to workout (Tues-Fri). Without any rest days in between, what is your advice for workouts during these days? Full body workouts back to back seem exhausting and don’t leave me any rest days to grow during the week but I know I need to keep my weekly volume up especially for the main/bigger muscle groups.
Hey Kells. I mean, that’s not an ideal training schedule, but not in a crippling kind of way. It shouldn’t even noticeably impact your results.
There’s more than one way to do it. For example, though, you could train like this:
Tuesday: Upper Body
Wednesday: Lower Body
Thursday: Upper Body
Friday: Lower Body
That would get you sweet results.
Unfortunately, not everyone has a normal fat distribution. I was doing the bony to beastly program and eating a huge calorie surplus. I didn’t have much fat but I had some belly fat. I gained a lot of muscle in 10 weeks but I also gained quite a bit of fat. All of my fat for some reason turns into visceral belly fat. My family constantly mocked me for my new belly.
I now plan on cutting and then going back to the program to gain more leanly.
Hey Austin, when you say that you’re gaining almost entirely visceral fat while bulking, is that because you’re noticing that your belly is getting bigger underneath your abs? That’s where visceral fat is stored, true. However, that’s also where all of the extra food you’re eating is being digested. And if your bulking diet is hard on your digestion, that’s where bloat would hang out, too.
It could be that you aren’t gaining visceral fat, you were just eating and digesting more food, maybe having a bit of trouble with the digestion part. That can make a guy look a bit pregnant until his body adapts to it.
Gaining a disproportionate amount of visceral fat while bulking is rare because bulking also means vigorously lifting weights, which reduces visceral fat storage. With a good bulking diet and an active lifestyle, that’d be even truer. Certainly not impossible to gain a bunch of visceral fat while bulking, though, and I think your plan sounds like a wise one 🙂
I think where it says “One of the best ways to stimulate muscle growth to eat in a big calorie surplus.” it should say “One of the best ways to stimulate muscle growth **is** to eat in a big calorie surplus.”
Shane, thanks for all the articles you’ve written. They’re, in my opinion, by far the best content for skinny guys on how to build muscle in the world. From linking studies to back-up your affirmation to the nuance you introduce by explaining the contradictions in some of them; from how you sprinkle the articles with motivation on the most difficult thing (eating more) to your eloquence and clarity in explaining everything; from how you make us understand how a lot of mainstream guidelines don’t completely apply to our body types to how you explain the most nuanced questions. You even answer every single fu**ing comment that gets written.
I cannot get tired of recommending this website and program to every skinny person I know. Thanks.
Thank you so much, Lautaro! For the kind words. That really means a lot. And thank you for spotting that typo, too. I’ve fixed it 🙂
Tortoise is hare in green shell, ohhh man how we missed it completely
[…] of weight gain depends on how skinny you are, how new to lifting you are, how lean you are, and how aggressive you want to be with your bulk. But the important thing is that you can at least some weight on the scale each […]
Hi I’m 14 and have been working out (with wieghts) for 15 months i have an 8 pack and ok biceps and I want to gain muscle in my arms fast without making my core less cut. But my problem is I am anorexic so every time I put on some mass i get scared and shave it off the same week.
Hey man, it sounds like the root of the issue has to do with anorexia. And to be completely honest with you, I’m not sure how bulking interacts with the psychology of anorexia. I’d hate to recommend something that makes it worse. What I can say, though, is that you don’t really need to worry about getting less cut. If you gain a bit of fat, you can always lose it later on. There’s no permanent change that takes place. Most skinny guys who bulk up go through a phase of overdoing it and getting a little fluffy. I know I have. It winds up working out in the end 🙂
I really hope you’re able to get to the bottom of this!
Thanks for the advice really nice of you to take time to get back to me like that nice to know there’s still good people out there. stay safe!
Hey Shane,
Thanks for all the work you do. I, and many others, appreciate it. I’ve been bulking for the past month or so, eating a surplus of calories and seeing steady gains on the scale. I went from 140-ish to 149 in about 4-5 weeks but haven’t moved the scale at all in the past week until this morning. Yesterday I decided to up my caloric intake from 3,000 to 3,500 calories and saw movement for the first time in a week. I suppose my metabolism has caught up to me, forcing me to eat even more than I first had to gain weight (you mentioned this might happen in one of your articles). My problem is, I feel like crap after eating so much, and don’t know if 3,500 calories is sustainable long term. I often want to throw up, and find myself hating greek yogurt and peanut butter more and more. My friend is in the same boat.
My question is this: At what point are mass gainers OK/recommended? Can I use a mass gainer to get me those extra 500 calories? Would eating a bowl of ice cream and a slice of pie every night do the same thing? Or do I need to just buckle down and stuff in one more plate of spaghetti?
Thanks man!!
Sam
Hey Sam, yeah, I hear ya, the deeper you get into a bulk, the more your metabolism will rev up, and the harder it gets to eat enough calories to keep gaining weight. That’s especially true with so-called “hardgainers.” We seem to have metabolisms that adapt more readily to overfeeding. There are studies where people eat, say, a thousand extra calories per day. Some people get fat, other people adapt to it by increasing their metabolisms (largely by subconsciously moving more).
The good news is, it doesn’t need to be sustainable, per se. You can go back to a fairly normal calorie intake afterwards. Your metabolism will gear back down as soon as you stop trying to gain weight. In fact, if your metabolism is bugging you, you can just take a break from bulking for a week or two. Eat according to your appetite. Let your metabolism settle down a bit. Just keep lifting and eating enough protein to ensure muscle maintenance. Even if you lose weight, you’ll just lose fat. And then you can go back to bulking afterwards. Best case, your metabolism has slowed down a bit. Worst case, it doesn’t, but at least you aren’t sick of overeating anymore.
And remember, bulking doesn’t need to be sustainable. Only maintenance does. And maintenance involves eating in line with your appetite. Don’t stress about the long-term impacts of this.
As for eating desserts or weight gainers, yep, that’s okay. Best to get around 80% of your calories from whole foods, but that’s not a hard and fast rule. And as you eat more junk food, it’s usually better to choose carb-heavy junk food. Ice cream and pie are totally fine, though (and are two of my favourites). When I was bulking with ice cream, I would often pick lower-fat ice creams, but I’m not sure that’s necessary. I was never strict about it. (Mind you, I often had to cut after bulking.)
Weight gainers are sort of like eating a slice of cake along with some whey protein. If you prefer cake and whey protein, that’s almost as good. The only real advantage to weight gainers is that they’re made of protein powder and maltodextrin—a starch. No extra fat. Quite similar to having an extra serving of pasta or rice in that sense.
Thanks Shane, great stuff here. Makes a lot of sense! One more question, I work in landscaping 3 days a week while at school, so I find it hard to eat enough while working due to the energy expenditure. Is there any merit to bulking on my off days and maintaining on my work days? Basically, eating a calorie surplus on the days I don’t work landscaping, and eating maintenance on the days I do? Does that work?
Also, sometimes I wonder if I should eat a caloric surplus on days that I don’t work out. If I work out 3 days a week and rest for 4, should I also be eating a caloric surplus on those 4 rest days? Is that when the majority of muscle is being built? Or on the 3 workout days? I guess I’m just curious about the science behind it all. It’s all so interesting, I can’t get enough!
Thanks again!
It’s probably good to eat in a calorie surplus for 1–2 days after training. Muscle-protein synthesis stays elevated for at least a day and often 2–3 days. If you’re training 3+ times per week, I’d just eat in a calorie surplus all week long unless you feel like you need a break from it or you aren’t able to manage it. If you can’t manage it on landscaping days, it is what it is. I wouldn’t recommend that, but if you can’t, you can’t. You’ll still make good progress overall 🙂
Hi! Thank you for the great articles, I have been reading all of them.
I am a beginner (literally) and started bulking up a week ago and I feel differences already. My main issue is that I gained 4 pounds already, from which most of them are fat. I am still ok with 13% body fat, but I just wouldn’t want to overdo that. Reading your article I saw that more 600 calories surplus is not necessarily good, from which I would like to ask what would be the optimal calorie intake for an average skinny guy. I think I have been overdoing calorie consumption thats why I am getting more overall fat.
Anyways, your articles have been so helpful and eye opening, thank you for the hard work!
Hey Matthew, glad you’re liking the articles and congrats on those four pounds!
Gaining around a pound per week works well for a lot of skinny guys when they first start bulking. To gain a pound per week, it takes a calorie surplus of roughly 500 extra calories per day. Mind you, it’s a moving target. Your metabolism will adapt. You’ll need to weigh yourself every week and adjust your calorie intake based on how much weight you’re gaining.
If you’re gaining a disproportionate amount of fat, you could try to follow a better hypertrophy training routine, make sure that you’re eating enough protein, make sure that you’re getting enough good sleep, and make sure that you’re getting a lot of your surplus calories from carbs. But if you’re doing all of that and still gaining too much fat, then gaining weight at a slower rate should solve it 🙂
[…] bulking: this was me. I was incredibly skinny and incredibly eager to bulk up, so I bulked up far too quickly. It’s not necessarily that I was doing anything wrong with my training, diet, or lifestyle, I […]
Hey Shane,
Hope you’re safe and well, and thanks for your articles man. They’re really insightful and helpful. I wish I’d found them sooner.
I’ve been working out for a couple of years but only really seriously for the past year or so, and even then some of my form for certain lifts has been way off. I’m at a stage where I’m visibly lean (around 10% body fat I’d say) with defined/toned muscles, and so I’ve definitely built muscle over that time. I’ve also lost weight (some fat and probably some muscle too in the past year).
However, despite the definition, I am very skinny and I currently weigh about 120lbs, which puts me slightly underweight for my height and age (5’8’’ and 19). I want to bulk up a bit, but at the same time I don’t want to put on too much fat because I enjoy being lean and have worked quite hard to get there. (I cleaned my diet up and hit the gym harder, with a more structured program).
I’m concerned that my newbie gains have been used up and from now on it will be hard to gain muscle without also gaining quite a lot of fat. I’ve never bulked before so I don’t know whether to go aggressive or lean, but I do want to bulk up a bit. I’d really just like to know where I stand in that regard: can I afford to bulk harder or should I take it slowly?
Hey Ben,
If you’re concerned about gaining fat and enjoy being visibly leaner, then I think you’ll prefer bulking more slowly and leanly. Gaining something like 0.5 pounds per week will probably suit you well 🙂
The other thing is, keep in mind that even if you gain a bit of fat, it’s not permanent. The idea is to build muscle as leanly as possible, but it’s common to mess it up a little bit, and that’s perfectly fine. Nothing bad will happen. It just means a few weeks of eating slightly fewer calories. No big deal. So there’s nothing really to worry about.
I’m a guy who likes being fairly lean, too. I’ve accidentally bulked a bit too hard in the past, gained some fat. But if anything, I think it’s helped me. I think it made it easier to build muscle. And then when the fat faded away, I was bigger and stronger than before, just as lean.
So take it slow, try to bulk leanly, but don’t stress about it. You’ll do great 🙂
Thanks Shane,
That helps a lot, I really appreciate it. Just couple of other quick questions. Firstly, what sort of surplus should I aim for to gain 0.5lbs per week. Also, I am near to my genetic potential, because although I don’t weigh a lot, my biceps are 12’’ when flexed. Does this mean my fat gains will be roughly equal to muscle gains?
Sorry, that should say am I near my genetic potential not I am.
Hey Ben, my pleasure!
A calorie surplus of around 250 calories per day will get you in the neighbourhood of gaining 0.5 pounds per week. Just keep in mind that it’s a moving target. You’ll need to weigh yourself and adjust your intake based on how much weight you’re gaining each week.
I doubt that your genetic limit is 12″ biceps. And even if it were, that’s just one muscle group anyway. You probably still have plenty of room for muscle growth 🙂
Thanks again Shane,
Really appreciate that advice. I’m so glad I’ve stumbled across these articles
Hi, it was great reading your site. I have started my weight training to gain muscle for almost 8 months now. I have got from 55kg to 62kg by increasing my food intake. As much as I see a transformation to a much better body, my gains are not massive. I am still disturbed that my abs are not showing. I have always been skinny fat and I find it hard to get rid of lower belly fat. I will run 5km once a week as I am worried that too must cardio might be counter-productive to my plan to gain muscle mass. I also workout in the gym 7 days a week for at least 1 hour each time. Not sure if I am over-training? As much as I want to continue to gain muscle mass, I hope to get visible abs as well. Please advise what should I do? Thanks.
Just to add. My current body fat is at 15.5%. Thanks
Hey Adrian, congrats on those 7 kilos, man! That’s awesome!
I wouldn’t stress too much about cardio interfering with your gains. The interference effect is often overstated, and most people who do a healthy amount of cardio will never see any downside to it. Cardio is great, and it’s an important part of being fit and healthy. Go for it without any worries 🙂
Your lifting routine sounds like a lot. It’s not necessarily that you’re overtraining, just that you probably aren’t training very efficiently. Most people are able to gain muscle at full speed with just 3–4 workouts per week. Mind you, some people prefer doing shorter or less efficient workouts more often, and that’s not necessarily a bad thing.
For visible abs, you’ll have to think about losing weight instead of gaining it. That’s the best way to encourage your body to burn fat for energy. You don’t need to do it now. No harm in continuing to focus on building muscle. But if it’s your main priority, best to dig into a calorie deficit to lose weight. Something like -0.5 kilos on the scale per week works very well.
Hey Shane, I am struggling to know when I am in a calorie surplus. I am 132 lbs 5’ 10” J have 13 inch biceps a 39 inch Chest and a 27 inch waist. I seem to plateau at 132. I am eating 3,000 calories a day and I train upper body three times a week and lower body twice. What can O do to increase my gains? I have never been able to get past 8% body fat.
Hey Phill, I hear ya, that’s tough. Those plateaus happen. The body just decides it doesn’t want to gain more weight. I’ve been there.
The good news is that the answer is fairly straightforward: more calories. Try eating 3,200 calories, see if that has you gaining any weight on the scale each week. If not, try 3,400. Keep adjusting your intake, weighing yourself, and adjusting again. Eventually, your weight will start rising again.
The bad news is: it’s really HARD! It’s hard to eat that many calories.
Check out this article: How to Eat More Calories. And even then, feel free to take breaks. Sometimes letting your weight rest at a plateau for a few weeks can be a welcome break from perpetually feeling full.
Great article, can’t believe this type of information is free.
I actually started eating more (tracking my calories) and lifting about a week ago. Gained 2lbs so far. I am 5’11, 16 years old, around 8-12% body fat and 144lbs. After reading your article I am scared about gaining more fat than muscle. Using a calorie calculator, my maintenance is 2,643-2,933 calories and the past week I’ve been consistently eating 3,200-3,500 calories a day plus working out/lifting (little to no cardio). I would like to keep my abs visible and my face as slim as possible, but also tired of being skinny and anxious to gain weight.
My question is what’s your opinion on what I should do. Should I keep eating the same? Or eat less? I have been skinny all my life with a higher metabolism. I am glad to send progress pictures since that’ll probably help.
Thank you
Hey Cody, congrats on those two pounds, man! And great job getting started. This is a great time for it. I wish I had started at your age.
2 pounds per week is fast. If you’re trying to keep your gains lean, I’d aim to gain more like 0.5–1 pound per week. But keep in mind that the first week is always a bit of an outlier. Some of the weight you gained is surely extra gut contents, maybe some extra glycogen and water retention. So I wouldn’t adjust your calorie intake yet. Hold steady for another week. You’re doing great 🙂
Now that you’re tracking your calorie intake and weight gain, you don’t need to estimate how many calories you burn anymore. Just measure how much weight you’re gaining each week and then adjust accordingly. If you keep gaining 2+ pounds per week, I’d remove 200 calories per day, see if that slows it down to a pound per week. And then keep adjusting by 200 calories each week until you’re only gaining 0.5–1 pound per week.
If you want help tracking your progress photos, check out The Bony to Beastly Program. We’ll teach you exactly how to take proper photos, measurements, and track your strength gains, and then we’ll track all of that with you in the community 🙂
(And since you’re under 18, if you do decide to join, make sure to talk it over with your parents first!)
Hey I got a question for the part which resonated with me the most-
“ Start of bulk:
180 pounds
158.4 pounds of lean mass
21.6 pounds of fat
12% body fat
End of aggressive bulk:
200 pounds
168.4 pounds of lean mass
31.6 pounds of fat
15.8% body fat
Results:
+10 pounds of muscle
+10 pounds of fat
+3.8% body fat”
What is the time period of this?
Hey Sebastian, when we’re talking about “aggressive” bulks, we’re usually talking about gaining around a pound per week. So to gain those 20 pounds, I’d give it 20 weeks—about 5–6 months. But you could also do it less aggressively, gaining most like 0.5 pounds per week. In that case, it would take closer to a year.
Hello,
I’m 20m, 5,8 1/2 and weigh 115 pounds. I think that makes me underweight. After reading this article i’m planning to gain 2lbs a week for say a month so I’m no longer underweight, and then slowing down to 1 lb a week. I don’t mind a bit of extra fat but would this be overdoing it?
Hey Matthew, we don’t really recommend that people gain more than a pound per week. The extra gains in fat usually aren’t worth it. Remember, the more fat you gain, the sooner you’ll need to end your bulk. But I’ve gained 2 pounds per week and liked the results. We’ve seen a lot of members do it. Some of them like the results, too. It depends on how much fat they gain.
If you want to bulk up super fast, that’s totally cool. But if you want my opinion, I’d recommend a steady pound per week. That’s still quite fast 🙂
Um, I’ve gained roughly 20 pounds in the last 2 months. That’s 2.5 pounds ish per week. Went from 133 pounds to 154 pounds. Will I die early or something because everywhere I research, it recommends about a pound a week. Just want to know if I’m going on the right path and if I should keep continuing forward.
Just to add, I’m not seeing too much fat. I believe I’ve gotten noticeably bigger, and the fat that i see on me, I cherish because for the last however many years of my life, I’ve not seen an inch of fat on me. Btw I was bulking about 4 months ago (Not as hard as I am now), and had managed to gain from 117 to 132, but had to stop because I went on vacation. (It took me about 4-5 months to go from 117 to 132).
Also, I was 5’7 before (at 120 ish pounds), am almost 5’9 now.
Congrats on the 20 pounds, man! That’s awesome!
That’s a little fast, yeah. But I’ve done it, too. I watched my roommate gain 27 pounds in a single month without gaining a noticeable amount of fat. We see that kind of thing all the time. Skinny guys are often able to gain weight quite quickly and leanly when they first start bulking.
The big risk factors are sedentariness, eating a bad diet, and having a waist circumference of over 40 inches (according to the NIH). To play it safe, some health organizations recommend keeping your waist circumference under 37 inches. To put that into context, the average man is relatively sedentary, eats a relatively poor diet, and has a waist circumference of 40.5 inches. If you do the opposite of that, if you’re active, eating a good diet, lifting weights, and bulking up, you can expect quite a few health benefits… provided you don’t gain such a tremendous amount of fat that you become over-fat.
If you’re going from a waist size of 28 inches to 36 inches, there’s no reason to think you’re harming your health. At least not as far as I can tell. Plus, gaining fat isn’t permanent. We can lose it. People with our genetics tend to be especially good at that. There’s no reason to be fearful of it.
You may do a better job of accomplishing your muscle-building goals with a slower rate of weight gain, though, especially as you get deeper into your bulk. If you gain more like 0.5–1 pound per week, your gains should be leaner, allowing you to continue bulking for longer, building more muscle as you go.
Good luck, man! You got this!
Thanks man!
Hey Shane, you do so much on your blogs. It’s incredible how much wisdom and science-based facts you pack into these articles.
This blog is awesome. You’re awesome.
However, I have a question that’s been bothering me. Indulge me a bit;
Say there is a man (call him Scar) who is 6’2 at 150 pounds, and another man (call him Simba) who is 5’2 at 100 pounds.
If both men decide to bulk at the same rate (say a pound-per-week gain), wouldn’t 1 pound look more significant on the shorter Simba than on the taller Scar?
I’m not sure if my point come across as clearly, but I’ll clarify if there are any problems.
Thank you, Tobi! That means a lot.
Taller guys look bigger, whereas shorter guys look more muscular. The 6’2 guy will look bigger in person because he’s taller and heavier. The 5’2 guy will look more muscular because his muscles are proportionally larger and fuller.
So, you’re right, yes. When a shorter guy gains a pound, it fills out a larger portion of his frame, contributing more to his muscularity. When a taller guy gains a pound, he gains just as much visual size, but it won’t contribute as much to his muscularity.
Taller guys need to gain more weight to fill out their frames. And even then, shorter guys still look stockier, fuller, and more muscular. There are advantages to both situations.
Interesting read. In comparing the tortoise and the hare approaches though I think you’re leaving out the fact that every time you cut weight about 25% of what you lose is lean mass (obvi that can be a variety of things that aren’t muscle).
So to cut 4 lbs of fat every 7 weeks you would need to cut roughly 6 lbs of total body weight, bringing the 7 weeks of gains down to 3.3 lbs. That would make the weekly gain is closer to .47 meaning it would take 42 weeks to build 20 lbs of muscle, much longer than the tortoise approach. Or am I missing something?
Hey Mitch, thank you.
Where’s this assumption coming from? The research is pretty mixed, but it isn’t that uncommon to see people gaining lean mass while cutting. Admittedly, that’s less true if people aren’t cutting properly, they’re nearing their genetic potential, or they’re cutting to extremely lean body-fat percentages (as bodybuilders do).
You’re right that not all lean mass is muscle. For example, it’s pretty common to store less glycogen when you’re eating less food. If you’re losing a small amount of weight, that loss of glycogen could make up a large percentage of the weight you lose. But you can only lose so much glycogen, so if you continue losing weight, it will make a smaller proportion of the weight you’re losing. And when you start eating more food again, your glycogen stores will replenish, giving you back the lean mass you lost.
I think if you cut properly and aren’t extreme about it, you can maintain virtually all of your muscle while cutting.