Illustration of a skinny guy building muscle on keto.

Are Keto Diets Good for Building Muscle?

Keto has been used as a weight-loss diet for over 200 years now. For example, in the 1970s, it saw a surge in popularity because of the Atkins Diet, which started with a strict ketogenic phase. But the fact that keto has a long history of helping people lose weight doesn’t tell us much about using keto to build muscle. Are there any advantages to doing keto when gaining muscle mass, gaining weight, and getting bigger?

Before and after results of a skinny guy gaining muscle mass on the ketogenic diet.

What is Keto?

What is the ketogenic diet? The ketogenic diet is a high-fat, moderate protein, and very-low-carb diet based around eating plenty of meats, eggs, cheeses, nuts, avocados, oils, and fibrous vegetables. For example, a meal might be a fatty cut of steak with a large portion of salad drizzled in olive oil.

What is the ketogenic bulking diet? Since this article is about how a ketogenic bulking diet performs against a traditional muscle-building diet, we’re going to use the best versions of both:

  • Standard bulking macros: 25% of calories from fat, 55% from carbs, 20% protein
  • Ketogenic bulking macros: 75% of calories from fat,  5% from carbs, 20% protein
Ketogaining: is keto good for building muscle mass?

Both of these diets have the perfect amount of protein, it’s just that one is high in carbohydrates, the other has almost none.

What does reducing carb intake accomplish? When you eat carbohydrates, your body breaks them down into a type of sugar called glucose, which is what the cells in your body use for energy. Your muscles and liver store sugar in the form of glycogen, your blood vessels transport it around as blood sugar, and your brain even runs on sugar.

If you stop eating carbs, though—either by fasting, starving, or eating a ketogenic diet—then your body can no longer use sugar as its main fuel source, so it begins breaking down fatty acids into ketone bodies (ketones). Over the course of the next few days, your cells switch over to using these ketones for fuel. This process is called ketosis, and it’s the foundation of the ketogenic diet.

What’s the purpose of ketosis? What’s exciting about ketosis is that your body starts burning your body fat for energy. Now, to be clear, any diet that allows you to get into a calorie deficit will allow you to lose fat just as quickly (study, study).

If you eat a high-fat diet, you’ll store more fat and burn more fat. If you eat a high-carb diet, you’ll store less fat and burn less fat. Either way, it balances out in the end. Still, a lot of people like the idea of directly using fatty acids for energy.

Perhaps a bigger advantage of the ketogenic diet is that it suppresses appetite, allowing people to feel fuller while eating fewer calories (meta-analysis). This can make the process of losing weight much less miserable.

But what if you aren’t trying to lose weight? What if you’re trying to build muscle?

How Does Keto Affect Weight Lifting and Muscle Growth?

When we lift weights, our muscles run on a carb-based fuel called glycogen. The more glycogen we have in our muscles, the longer we can work out before our muscles run out of fuel.

Illustration of a bodybuilder building muscle on a ketogenic diet.

If we switch to a ketogenic diet, there are fewer carbs available, and our muscles won’t store as much glycogen as they normally do (study, study). Because our muscles aren’t as pumped full of fuel, they’ll look a little smaller and flatter, and they won’t have quite as much strength endurance. Mind you, this doesn’t have a big impact on strength training (study, study). There aren’t many reps per set (1–5 reps) and there aren’t many sets per workout. It’s a style of training that doesn’t require much muscle fuel, just muscle strength.

However, that’s not necessarily relevant if we’re trying to build muscle. Strength training is designed to help people contract their muscles more forcefully to make them stronger for their size. Some muscle mass comes along as a byproduct, but when compared with other styles of weight lifting, strength training isn’t very good for building muscle.

If you’re trying to get bigger and stronger, then you’ll want to do hypertrophy training. That means doing moderate-rep sets, typically in the 6–20 rep range but sometimes expanding that to 4–40 reps. That helps us lift more total poundage each workout (higher training volume), and that means digging deeper into our glycogen stores. Thus, having more glycogen becomes an advantage.

Illustration of a man doing strength training on a ketogenic diet.

Furthermore, strength training often tries to minimize the range of motion to improve leverage: sitting back and using a wide stance while squatting, benching with a big arch and a wide grip, and deadlifting with a sumo stance (especially in the lighter weight classes). With hypertrophy training, we want to do the opposite, using a larger effective range of motion. This means doing quite a bit more work for every rep that we do. And so, again, having more glycogen becomes an advantage.

Mind you, our muscles store quite a bit of glycogen, and even with hypertrophy training, we won’t run out of glycogen unless we train a single muscle group for several hours in a row. Thing is, we aren’t just trying to avoid running out of glycogen, we’re trying to get the performance-enhancing effects of being absolutely packed full of glycogen. So when working out to gain muscle mass, most research shows that the more glycogen we have in our muscles, the more muscle we can build (studystudy, study).

In fact, simply having more glycogen in our muscles seems to reduce muscle damage while speeding up muscle growth, allowing us to construct more new muscle tissue (study). So regardless of which type of training we’re doing, if we’re trying to gain muscle mass, keto isn’t the best approach. It’s better to eat more carbohydrates (study).

Furthermore, weight lifting stresses our bodies. It’s a good type of stress, but it’s stress nonetheless. Higher-carb diets help manage this stress, keeping our testosterone production high and our cortisol production low. Low-carb diets, on the other hand, can cause testosterone to plummet and cortisol to rise (study). This is important because having higher testosterone can help us build more muscle more leanly, whereas higher cortisol (a stress hormone) can reduce muscle growth, increase fat storage, and suppress our immune system.

Finally, there’s insulin, which is used to shuttle nutrients towards fat storage or muscle gain. Both protein and carbs will stimulate insulin production, meaning that even a ketogenic diet will produce enough insulin to allow for muscle growth. However, eating more carbs will raise insulin production even higher, and in the context of lifting weights and building muscle, that’s a good thing. Higher insulin production will reduce muscle damage and allow for more muscle growth (study, study).

That gives us a laundry list of benefits from a higher intake of carbs:

  • Bigger and fuller muscles
  • You might be able to lift more reps
  • You might have more strength endurance
  • Higher testosterone
  • Higher insulin
  • Lower cortisol
  • Less muscle damage
  • More muscle growth
Illustration of a bodybuilder gaining muscle mass on keto.

What’s interesting is that these performance-enhancing and muscle-building benefits of carbohydrates are well known, even in the ketogenic communities. As a result, there are modified versions of the ketogenic diet that are designed for people who are trying to build muscle:

  • Cyclical Ketogenic Diet (CKD): The cyclical ketogenic diet allows people to load up on carbs 1–2 times per week, allowing them to get some of the muscle-building benefits of a higher-carb diet.
  • Targeted Ketogenic Diet (TKD): The targeted ketogenic diet allows people to eat a small number of carbohydrates before working out, allowing them to get some of the performance-enhancing effects of carbohydrates.

These might help mitigate some, or even many, of the downsides of bulking on a low-carb diet. However, they don’t offer any advantages over a diet that’s consistently higher in carbohydrates. In fact, a recent weight training study on cyclical ketogenic diets found that the keto group built less muscle mass, gained less strength, and lost less fat than the group eating a typical bodybuilding diet. So even with a cyclical ketogenic diet, the muscle-building results are still underwhelming.

Does Keto Reduce Fat Gain While Building Muscle?

Given the paucity of research, it’s hard to say for sure, and the effect might not be large, but we’d likely gain more fat while bulking on a ketogenic diet (provided that we’re able to eat enough calories to even gain weight in the first place). When we’re in a calorie surplus, our body is presented with extra nutrients. It can do a few things with those nutrients:

  • Carbs can easily be stored as muscle glycogen, improving lifting performance and muscle growth
  • Protein can be burned off as body heat and used to build muscle
  • Fat can easily be stored as body fat

In this situation, the extra carbs and protein are helping you build muscle leanly. The fat, on the other hand, isn’t causing any extra muscle growth, and it’s more likely to be stored as body fat. This lines up with what we see in the research, where keto seems to slightly reduce muscle growth and fat loss when combined with a weight lifting program.

Illustration of a skinny hardgainer eating a feast in his attempt to bulk up, gain weight. and build muscle.

To be fair, it’s possible for protein and carbs to transform into fat (de novo lipogenesis). However, this rarely happens to people who exercise. Even when it does, the conversion is so inefficient that only a fraction of the carbs and proteins actually wind up being stored as body fat.

What usually winds up happening when you’re building muscle on a higher-carb diet is that you consume some fat (say 20% of your diet) and your body will wind up storing some of it directly as body fat. This means that even on a higher-carb diet, yes, you can gain fat. However, because it’s less abundant, you’ll gain less of it.

Now, the caveat to this is that if you’re eating in a large calorie surplus for a long period of time without working out (without using any of the glycogen in your muscles), then it doesn’t matter as much what your macros are. Both the high-carb and the high-fat diets are going to cause a lot of body-fat gains. That isn’t relevant to us, though.

Before and after photo showing that a typical bodybuilding diet produces leaner gains than building muscle on keto.
Lean muscle growth with a traditional bodybuilding diet.

Bulking on a high-carb diet should yield leaner muscle growth than bulking on a ketogenic diet. But again, given the limited amount of research, it’s hard to say for sure how the results would compare, and the effect may be small enough that it doesn’t matter.

Are There Advantages to Building Muscle on Keto?

Most people doing keto aren’t interested in building muscle, they’re interested in losing weight. The reason they love keto is that it suppresses their appetite, allowing them to eat until they’re full while still losing weight. In fact, because overweight people have so much energy available in their body fat, they’re often able to build a little bit of muscle even while losing weight.

Illustration of a man weight training on keto.

If you want to build muscle quickly, you need to be in a calorie surplus (study, studystudy), but that’s usually not the top priority for someone who’s overweight. For them, weight loss is usually better, even if it drastically slows down muscle growth.

If you’re a skinny guy who’s trying to bulk up, though, appetite suppression can be a real problem. It’s already hard to eat enough calories while bulking, and ketogenic diets only make that harder.

It’s especially hard to bulk on keto during the first month or two of switching over. Your body won’t be used to digesting so much fat, which can cause indigestion. It’s also common to feel fatigued which is known as the “keto flu.” After adapting to the diet, it becomes a little easier to eat more calories. Even then, though, it can still be hard to bulk on keto.

For example, Menno Henselmans, MSc, is a researcher who loves the ketogenic diet. If he has an overweight client who wants to lose fat while building muscle, he’ll often recommend it. If someone’s goal is to bulk up, though, Henselmans flips his recommendation around. Here’s a quote from an interview he did with Mike Israetel, PhD:

You rarely see people who bulk in ketosis. It’s not because it’s not physiologically possible, it’s because, practically, it really sucks.

Even Dom D’Agostino, PhD, who is famous for promoting the ketogenic diet on The Tim Ferriss Show and The Joe Rogan Experience, doesn’t recommend using keto for bulking. When asked about using the ketogenic diet to gain muscle, he said that it might help men over 40 who struggle to digest carbohydrates, but that it isn’t an optimal bulking diet for the average person.

There are others who are slightly more enthusiastic about it. For example, Nate Martins, an advocate of bulking on keto, wrote:

We’re here to rewrite the narrative that building muscle on keto is impossible. Both science and subjective experiences speak to the ability to maintain, or sometimes gain, muscle mass while on keto.

What I find interesting about that statement is that even though Martins is clearly a fan of the ketogenic diet, when it comes to bulking, he’s setting the bar very low. He’s not saying that bulking on keto is better, easier, or quicker. His claim is simply that it’s sometimes possible to gain muscle mass on a ketogenic diet.

As far as I can tell, nobody is arguing that it’s better to bulk on keto. They’re just arguing that it’s possible to bulk on keto.

There’s no reason to think that they’re wrong. It’s surely possible to bulk on a ketogenic diet… right?

What Happens If You Bulk On Keto?

Up until recently, there was only one high-quality study investigating what happens when we bulk on a ketogenic diet. The results are interesting. Not surprising, per se, but interesting.

The researchers split the study participants into a ketogenic group and a high-carb group:

  • High-Carb: 25% from fat, ~55% carbs, 2g/kg protein
  • Ketogenic: ~70% fat, less than 10% carbs, 2g/kg protein

Both groups were put on a 4-day/week lifting program. Both groups were put on a high-calorie bulking diet. After eight weeks, here’s what happened:

The study found that high-carb diets produce much more muscle growth than ketogenic diets, but it's not that simple.
  • High Carb: +3 pounds muscle, -1 pound fat
  • Ketogenic: -1 pound muscle, -2 pounds fat

The high-carb group gained a substantial amount of muscle while losing a little bit of fat. That might not seem like much muscle growth in 8 weeks, but these were experienced lifters, so that’s to be expected.

The ketogenic group was more interesting. They lost a little bit of muscle during their 8-week bulk, so the researchers concluded that ketogenic diets weren’t effective for building muscle, even in a calorie surplus. However, there’s a huge flaw here that completely undoes their finding—the ketogenic group wasn’t in a calorie surplus. They weren’t bulking.

It turns out that the ketogenic diet is so effective at getting people into a calorie deficit that even though the keto participants were trying to bulk, they simply weren’t able to. Struggling to eat enough calories to gain weight is a common struggle for hardgainers, but it’s surprising to see a group of regular people unable to gain weight like that.

As a naturally skinny guy who always had trouble eating enough calories to gain weight, this study terrifies me. I had a nightmare last night about opening my cupboard to grab a snack, but instead of finding 500-calorie portions of trail mix, it was packed full of avocados.

Now, there’s always the possibility that a single study could have outlier results, but these findings line up with previous research:

  • A case study found that after switching to a ketogenic diet, four out of the five lifters started losing weight and stopped gaining muscle mass. One of the researchers, Eric Helms, PhD, commented that “if your goal is to put on muscle mass, it’s probably best to have some level of carbohydrate in your diet.” Based on his review of the research, he recommends a bare minimum of one gram of carbs per pound bodyweight per day.
  • In a study on CrossFitters, the control group gained weight and gained muscle mass, whereas the ketogenic group lost weight and lost muscle.
  • A couple of other studies found that when strength athletes switched to a ketogenic diet, they lost weight and stopped being able to gain any muscle mass.

So far, so bad. All five of these studies show participants failing in their efforts to bulk up while eating a ketogenic diet. They were lifting weights, eating enough protein, and trying to build muscle, but they couldn’t.

However, these studies just show that ketogenic diets suppress appetite. Since none of the participants were able to gain weight, we don’t actually know what happens in a calorie surplus… which is where the controversy begins.

What About the Other Keto Bulking Study

Since we’re talking about bulking on a ketogenic diet, we should probably mention the elephant in the room. There’s an oft-cited sorta-study showing that the ketogenic diet can produce rapid muscle growth with simultaneous fat loss.

In this study, the researchers split the participants into two groups:

  • High-Carb: 25% from fat, 55% carbs, 20% protein
  • Ketogenic: 75% fat,  5% carbs, 20% protein

After 11 weeks of doing a 3-day/week lifting program, their results were:

  • High-Carb: +4.8 pounds of muscle, -3.3 pounds of fat
  • Ketogenic: +9.5 pounds of muscle, -4.8 pounds of fat

Now, that might seem like a lot of muscle growth, and it absolutely is, but that alone doesn’t make this study suspect. As we covered in our newbie gains article, there are plenty of studies showing tremendous amounts of muscle growth, especially in untrained lifters:

  • This study on beginners found that guys were able to gain 9 pounds of muscle during their first 8 weeks of working out.
  • In this study, a group of untrained beginners were able to gain an average of 12 pounds of muscle during their first 10 weeks of working out.
  • In another study, beginners were able to gain 15 pounds of muscle during their first 12 weeks of lifting weights.

These three studies all show high rates of muscle growth in guys who lift weights, eat in a calorie surplus, and eat enough protein. It’s not that unreasonable to assume that guys aggressively bulking on a ketogenic diet could get similar rates of muscle growth.

However, this study was conducted on experienced lifters, who tend to build muscle much more slowly. Moreover, the ketogenic diet outperformed the traditional bulking diet by a large margin, which is the opposite of what we’d expect.

Is this what happens when keto lifters are able to get into a calorie surplus? Do they really gain muscle twice as quickly?

Well, we don’t really know for sure, but probably not. The reason I call this a sorta-study is that it isn’t a study, per se, it’s a research poster. It’s a one-page summary of a study that doesn’t seem to be available anymore.

Perhaps relevantly, this is the same research group that published a controversial study on HMB, showing that it produced more muscle growth than high doses of steroids. That study attracted quite a lot of scrutiny as well, and the results couldn’t be replicated by other researchers (study).

Anyway, to figure out what to make of this research, I reached out to Brad Dieter, PhD, a researcher who’s written about the ketogenic diet. He told me:

The literature surrounding ketogenic diets and muscle growth is still nascent and has methodological issues that prevent us from drawing any real meaningful conclusions. Currently, from my perspective, there isn’t much data one can use to suggest it is superior to other approaches or to show it is not inferior to other approaches

So there’s not a lot that we can do with this one study unless other teams of researchers start getting similar findings.

New Research on Keto for Muscle Growth

The Schoenfeld Keto Study

Fortunately, leading hypertrophy researcher Dr Brad Schoenfeld recently conducted his own research into whether ketogenic diets were effective for building muscle. His study found, in keeping with the overall body of evidence, that ketogenic diets weren’t ideal for building muscle.

However, also in keeping with earlier research, one of the main reasons that the ketogenic diet failed to produce as much muscle growth as the higher-carb diet was that the participants in the ketogenic group, even though they were instructed to be in a calorie surplus, failed to eat enough calories to gain weight.

Dr Schoenfeld summarized these findings by saying, “when considering this study in context with the body of literature, a general take-home would be that the keto diet is a viable strategy for losing body fat, but would not be ideal if your goals are to maximize strength and hypertrophy.”

The Vargas-Molina Keto Study

We also have a 2020 study from Vargas-Molina et al showing that, once again, the participants eating a ketogenic diet failed to gain muscle, largely because they weren’t able to get into a calorie surplus. However, even if the keto participants had been able to get into a calorie surplus, hypertrophy training tends to be done in moderate-to-high rep ranges, which benefits from having plenty of glycogen in our muscles. Keto diets tend to reduce the glycogen we store in our muscles. As a result, the non-keto group gained significantly more muscle size and strength than the keto group.

The current evidence doesn’t suggest that it’s impossible to gain muscle on a ketogenic diet, but its effects on appetite and high-intensity exercise performance make it hard to view keto as the ideal dietary approach for gaining muscle. 

Eric Trexler, PhD

The Adam Tzur Study: The Ketogenic Diet’s Effect on Bodybuilders

Another 2020 study by Adam Tzur and Brandon Roberts, PhD, found that keto reduces glycogen storage and appetite, leading them to conclude that ketogenic diets are “suboptimal for bulking and gaining lean mass.”

The Paoli Study: Keto vs Conventional Bodybuilding Diets for Building Muscle

The most recent study pitting the ketogenic diet against a conventional bodybuilding diet is a 2021 paper by Paoli et al. They had one group of participants eating a ketogenic diet, getting just 5% of their calories from carbohydrates. The other group was put on a conventional bodybuilding diet, getting 55% of their calories from carbohydrates.

Graph showing that the group eating a higher-carbohydrate diet gained muscle mass than the group eating a ketogenic diet.
The conventional bulking diet yielded 4x more muscle growth than keto.

Both groups were instructed to eat at maintenance—neither gaining nor losing weight—and to follow a lifting program. But the keto group had trouble eating enough calories, failed to maintain their weight, and so didn’t build as much muscle as the group eating the higher-carb diet. This again goes to show that keto can be good for losing weight but isn’t ideal for bulking up, building muscle, or gaining strength, especially for people who struggle to eat enough calories to gain weight.

As always, it’s important to note that when eating a ketogenic diet, our muscles store less glycogen, making us appear less muscular. This doesn’t necessarily mean that we have less contractile tissue, though, just that our muscles look flatter and have less muscular endurance. In fact, it could be that some or even all of these differences in muscle growth are explained by differences in glycogen, not in contractile tissue.

Overall, this study once again shows that ketogenic diets aren’t the best default diet when trying to bulk up. It’s certainly possible to build muscle while doing keto, but it does become quite a bit more difficult.

How to Build Muscle On Keto

 The ketogenic diet is so effective at suppressing appetite that it can make bulking quite difficult. Furthermore, there are no known advantages to using keto for building muscle. Still, there are other reasons why someone might want to follow a ketogenic diet, such as having trouble digesting carbs, and it’s certainly physiologically possible to build muscle while doing it.

Before and after results of building muscle on keto.

Here’s how to bulk on a ketogenic diet:

  • Follow a good bulking program: Ketogenic diets are commonly paired with strength training but remember that strength training isn’t designed to stimulate muscle growth. If you’re trying to bulk up, choose a hypertrophy program instead. You’ll build muscle more quickly and leanly.
  • Eat enough calories to gain weight: for a beginner, we usually recommend gaining about a pound every week, which means eating around 500 extra calories each day (which is usually a total of around 18–22 calories per pound body weight per day). If a week goes by and you don’t gain weight, add another 200 daily calories. Adjusting every week will allow you to keep gaining weight even as your metabolism adapts to your bulking diet. For more experienced lifters, gaining 0.5 pounds per week usually works better.
  • Eat enough protein (0.8g/lb/day): eating around 0.8 grams of protein per day should allow you to build muscle at a maximal pace while having no trouble staying in ketosis. This is usually pretty easy while on a ketogenic diet, and most guys doing keto naturally eat enough protein for muscle growth.
  • Eat mostly whole foods: on a ketogenic diet, this is going to mean eating lots of unprocessed meat, dairy, eggs, nuts, avocados, oils, and fibrous veggies. Avoid processed meats. Watch out for letting your saturated fat intake rise much higher than 10% of your total calories, especially if it’s coming from processed foods.
  • Eat a diet that’s easy on the appetite and easy to digest: You might want to lean towards ground meat, which is easier to chew and digest, making it easier to get into a calorie surplus. You’ll also want to drizzle your salads with plenty of olive oil, adding a ton of nutritious fat calories to an otherwise low-calorie part of your meals. If that’s not enough to get you into a calorie surplus, you may even want to sip (or shoot) olive oil.
  • Get enough quality sleep: you’ll want 7.5–9 hours of good quality sleep each night. That might not always be possible, but the more sleep you can get, the more quickly and leanly you’ll build muscle.

The main challenge of bulking on a ketogenic diet will be eating enough calories to gain weight. However, there are ways around that, and that just so happens to be our specialty. Here’s our guide for how to eat more calories. It’s not specific to the ketogenic diet, but all the same principles still apply.

During my final bulk, gaining my final 15 pounds, I ate a ton of ground beef, drank a bunch of raw eggs, and took a shot of extra-virgin olive oil every night. It wasn’t my favourite way to eat, and nowadays I rely on trail mix and smoothies instead, but those couple little tricks made it much easier to get into a calorie surplus.

Although keto probably isn’t ideal for building muscle, with some cleverness, you should still be able to bulk up with it.

Summary

Most research shows that building muscle while following a ketogenic diet is possible but not ideal. Most study participants wind up accidentally losing weight while doing keto, even when instructed to eat in a calorie surplus (systematic review, meta-analysis). And in all cases, people build muscle faster and more leanly by eating a conventional muscle-building diet.

If you choose to bulk on a ketogenic diet, you can indeed still build muscle. Just because it isn’t ideal doesn’t mean it’s impossible. The trick is to make sure that you’re eating in a calorie surplus—that you’re gradually gaining weight. For most people, gaining 0.5–1 pound per week is ideal while bulking. The other trick is to get most of your calories from a good mix of fats, including plenty of meat and dairy, but also nuts, fish, avocados, and olive oil.

Illustration showing the Bony to Beastly Bulking Program

If you want more muscle-building information, we have a free bulking newsletter for skinny guys. If you want a full bulking program, including a 5-month workout routine, diet guide, recipe book, and online coaching, check out our Bony to Beastly Bulking Program. Or, if you want an intermediate bulking routine, check out our Outlift Intermediate Bulking Program.

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.