The ketogenic diet has been used as a weight-loss diet for over 200 years now. In the 70s, for example, it saw a surge in popularity because of the Atkins Diet, which started off with a strict ketogenic phase. But the fact that it has a long history of helping people lose weight doesn’t tell us much about whether it’s effective for bulking up. Are there any advantages to using keto for building muscle, gaining weight, and getting bigger?
In this article, we cover:
- How does keto affect lifting and muscle growth?
- What happens if you bulk on a ketogenic diet?
- Should you bulk on a ketogenic diet?
- How do you bulk on a ketogenic diet?
Let’s dive in.
What is the Ketogenic Diet?
What is the ketogenic diet? The ketogenic diet is a high-fat, moderate protein, 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 bulking 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
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 restricting carbs 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 lifting and muscle growth?
When you lift weights, your muscles run on a carb-based fuel called glycogen. The more glycogen you have in your muscles, the longer you can train before your muscles start to get fatigued.
When you switch to a ketogenic diet, there are fewer carbs available, and your muscles won’t store as much glycogen as they normally do (study, study). Because your 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.
This doesn’t have a big impact 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, strength training isn’t very good for gaining muscle size. Strength training is great for getting the neural gains that will make you stronger for your size, but if you’re trying to bulk up, that’s not the kind of adaptation that you’re fighting for.
If your goal is to bulk up—to gain muscle size—then you’ll want to be doing a hypertrophy program. That means doing higher-rep sets, typically in the 6–12 rep range. This means lifting more total poundage each workout (higher volume), which means digging deeper into your glycogen stores. Our muscles store quite a bit of glycogen, though, and even with hypertrophy training, you won’t run out of glycogen unless you train a single muscle group for several hours in a row.
However, we aren’t just trying to avoid completely running out of glycogen, we’re trying to get the performance-enhancing effects of being absolutely packed full of glycogen. When it comes to workouts that are designed to stimulate muscle growth, most research shows that the more glycogen you have in your muscles, the better (study, study, study).
In fact, simply having more glycogen in your muscles seems to reduces muscle damage while speeding up muscle growth, allowing us to construct more new muscle tissue (study). So regardless of which type of training you’re doing, if you’re trying to build muscle, it’s probably best to eat plenty of carbohydrates (study).
Furthermore, lifting weights stresses our bodies. It’s a good type of stress, but it’s stress nonetheless. High-carb diets help manage this stress, keeping testosterone production high and cortisol production low. Low-carb diets, on the other hand, cause testosterone to plummet and cortisol to rise (study). This is important because having higher testosterone can help you 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
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 amount 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. They’re simply less bad.
Does keto reduce fat gain while bulking?
Given the paucity of research, it’s hard to say for sure, and the effect might not be large, but you’ll likely gain more fat while bulking on ketogenic diet.
When you’re in a calorie surplus, your 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.
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 bulking 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 gain. That isn’t relevant to us, though.
Bulking on a high-carb diet should yield leaner gains than bulking on a ketogenic diet. But again, given the limited amount of research, it’s hard to say for sure, and the effect may be small enough that it doesn’t matter.
Why would you use keto for bulking?
Most people doing keto aren’t interested in bulking up, they’re interested in losing weight. The reason they love keto is because 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.
If you want to build muscle quickly, you need to be in a calorie surplus (study, study, study), 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, MFA, who wrote the most popular guide for bulking on keto, says:
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 when you bulk on a ketogenic diet?
There’s only one high-quality study investigating what happens when you 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:
- 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 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 it 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 because 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).
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, which at this point seems unlikely.
How to Bulk On a Ketogenic Diet
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.
However, 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.
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 bodyweight 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 the ketogenic diet probably isn’t ideal for building muscle, with some cleverness, you should still be able to bulk up with it.