The aversion that most lifters have for low-carb zealotry is well deserved. This latest generation of keto gurus carries all the trademark signs of the worst kind of idiocy. But is it all bad? I mean, if Navy SEALs are doing it and Dr. Oz is talking about it, there's gotta be something there right?
All jokes aside, we do need to make sure we aren't throwing the baby out with the bathwater by writing off an entire body of research. But the biggest problem with keto is that many of those pushing it haven't done their homework.
Should those who are physically active continue eating low-carb? It’s a fair question for those wanting to follow a ketogenic diet for better health, and that’s why we’ll be exploring the main areas of ketosis for physical performance.
The ketogenic diet and ketosis have been used traditionally by physicians and other professionals for a few different medical reasons, including improving the health of those with diabetes and treating neurological disorders like epilepsy.
But now, we’ve begun to explore other factors where the ketogenic diet can have a positive effect, including mental focus, weight loss, and in this article, ketosis for physical performance.
The Ketogenic Diet for Exercise
While the emphasis for exercise is usually on high carbohydrate intake, the ketogenic diet takes a low-carb approach to energy. Those on a ketogenic diet generally stay within a range of 30-50 grams of carbs per day, and a large amount of food in the diet comes from fat.
The ketogenic diet involves a dietary breakdown of:
- Low carbohydrate intake
- Moderate protein intake
- High fat intake
The low intake of carbs is meant to put the dieter into ketosis, where the body creates ketones from fat stores to use as the main energy source, instead of carbs, for the body and even partly for the brain. Molecules known as ketones are produced during the process.
This means that someone exercising while eating a ketogenic diet is going to be using primarily fat as fuel for their physical activity.
Misconceptions about Ketosis for Physical Performance
A long-held belief among the nutrition and medical community is that carbohydrates must make up a high portion of your diet in order to maintain physical performance at an ideal level. This belief mostly stems from studies in the last 100 years looking at muscle glycogen and its link to high intensity exercise.
However, there are a few reasons to question this thought process:
- We’ve observed cultures that didn’t eat in line with the carb-heavy philosophy, such as the Inuit people in the Canadian and Alaskan Arctic regions. Before their diets changed a lot, scientists were able to observe their traditional diet and see that it contained virtually no known carbohydrates, yet they were able to function normally physically.
- Demographic evidence of past European cultures has shown them living as primarily hunters without any noted physical impediments.
- While diets with more carbohydrates may prove better for higher-intensity, short-term forms of exercise, the limitations of the ketogenic diet for physical performance have been over exaggerated. In fact, ketosis can have a healthy role in relation physical activity for most individuals.
Let’s take a look at the differences associated with using ketones for fuel versus using carbs for fuel.
Fat Adaptation in Ketosis
With a ketogenic or other low carb diet, the body experiences fat adaptation, or keto-adaption, where it becomes more efficient at burning fat and ketones for fuel. This adaptation can be strong and have a great impact on the fat burning process during exercise.
During a recent study, ultra-endurance athletes who were on a ketogenic diet for an average of 20 months were shown to burn up to 2.3 times more fat than the high-carb group during a three-hour run. The study also found that muscle glycogen use and repletion during and after the exercise was similar between the low-carb and high-carb groups. This is a significant demonstration of the power of keto-adaptation for exercise.
Endurance Exercise and Ketosis
As we’ve established, fat can be used for energy when carbs aren’t available for use. While carbs do provide more fuel for the body to perform at higher intensities, fat is what provides more energy during exercise at lower intensities.
However, this might be open to question as well. In one study, researchers recorded athletes following a ketogenic diet had burned mostly fat during exercise at up to 70% of their max intensity, while the high-carb athletes burned fat at 55%. This again demonstrates the increased effectiveness of ketosis for fuel during exercise when a person’s body has adapted to burning primarily fat for energy.
With this in mind, it’s still important to recognize that some elite athletes may require energy more quickly than the rate at which they can get it from fat, and more research is needed on the subject to know the details for sure. That being said, a low-carb ketogenic diet can be helpful in regards to exercise for:
- Preventing tiredness when doing longer exercise
- Perform low-to-moderate intensity levels of exercise through keto-adaptation
- Improving health and losing more fat through regular exercise and low-carb eating
- Maintaining blood glucose during exercise
- Adapting the body to burning more fat, which might be able to help the body preserve glycogen in the muscles during exercise
Muscle Growth and Ketosis
We don’t currently have research showing a specific benefit of ketogenic diets over higher carb diets for muscle growth during strength or high-intensity exercises. That being said, there are some studies show that in addition to using more fat as fuel, low-carb diets can also help preserve muscle glycogen for some athletes. Plus, a ketogenic diet has the advantage of teaching the body to more easily turn to fat burning for fuel.
However, that doesn’t mean it’s necessary to turn to a very high carb diet to see success in muscle growth and performance. In fact, a diet that is higher in protein and more moderate in carb intake might be the best for achieving ideal body composition and muscle growth for most active people and some sports athletes.
An Early Account of Ketogenic Diet Performance
Let’s take a second to travel back over a hundred years ago to one of the earliest recorded examples of a ketogenic diet for intense physical performance.
The evidence was shown in a written diary published in the New York Herald in the Fall of 1880. The diary belonged to Lt. Frederick Schwatka, a West Point and Bellevue Hospital Medical College graduate and leader of an expedition between 1878 to 1880 to look for the lost Royal Navy Franklin expedition.
The group consisted of 18 people made up of three Inuit families, four Caucasians, and three dog sleds with 44 dogs. They began on the west coast of Hudson’s Bay with a month’s supply of food that was mostly walrus blubber (fat). Once that was gone, they had to subsist only on food from hunting and fishing (animals foods full of protein and fats). The journey on foot spanned 3,000 miles through snow, ice, and tundra.
By May of 1880, the whole team and their dogs returned safely to the Bay! This older account is a great example of the human ability to perform exceptional physical feats on very low, if any, amounts of carbs.
Benefits of Ketosis for Athletes
A lower carb intake does have some potential benefits for certain types of athletes. For example:
- Some research shows that the preservation of glycogen stores from a ketogenic diet can prevent endurance athletes from “hitting the wall” while performing endurance exercises.
- Keto-adaptation can lead to less reliance on carbs during endurance exercise, which can help athletes during events where there is limited access to food or those who can’t easily digest carbs during exercise.
- A diet that promotes more fat loss is important for improve the ratio of fat to muscle, which is crucial for those looking to improve their exercise performance or meet certain weight goals for their sport, such as in wrestling, weightlifting, and boxing.
- The practice of exercising while glycogen stores are low is a training technique popular for improving the function of mitochondria, enzymes, and fat usage to improve overall health and physical performance long-term.
- Eating a ketogenic diet might also be a good diet practice for an athlete’s off season as they maintain their health while resting.
What It All Means for Serious Lifters and Athletes
So let's address the elephant in the room. The subjects in most keto studies are endurance athletes. Why should anyone who wants to build muscle and get stronger be concerned with any of this?
Because it sheds light on a potential solution to one of the most perplexing paradoxes that bodybuilders and strength athletes have faced throughout time: how to get leaner while preserving as much muscle and strength as possible.
When carb-fueled strength athletes seek to burn body fat, they typically reduce their overall caloric intake by consuming less carbs and fat while maintaining or increasing their protein intake. Unless athletes are fat adapted (burning ketones for fuel rather than glucose), however, this does not reduce dependence on glucose while performing the physical activity needed to burn that fat off.
To make up for this energy deficit, the body needs to find fuel somewhere. To generate glucose, cortisol release stimulates gluconeogenesis, whereby amino acids get converted into glucose via the liver. Those amino acids can come from ingested protein or from muscle catabolism. Either way, in a lower carb but non-fat adapted state, you're potentially misusing the protein that you're eating or, even worse, you might be breaking down precious muscle mass.
Keto studies demonstrate is that, rather than depleting athletes' glycogen levels, fat adaptation allows them to become far more efficient at utilizing glycogen. Increased access to fat as fuel leads to less dependence on glycogen and less potential muscle catabolism.
Placed in the context of other studies that demonstrate superior muscle retention on the keto diet over traditional diets, there's a pretty good case for fat adaptation as a way for strength athletes to lean out while preserving strength and muscle.
But the real question is: What should a low carb diet for lifters and athletes really look like?
When you delve into the deepest, darkest corners of the current keto trend, you hear lots of really poor understandings of what constitutes a proper low carb diet for athletes, along with enough bad advice to make you wonder how these people ever made it to adulthood.
Dumb things like:
- Avoid vegetables because they've got carbs and can kick you out of ketosis.
- You never need carbs when you're keto adapted, no matter what your activity levels are. Your daily total carb intake must be below 30 grams!
- You don't need as much protein on the keto diet, and eating more than 0.8 grams per pound of bodyweight could get you kicked out of ketosis.
This stuff rightfully scares the crap out of anyone whose fitness goals are loftier than doing Zumba without dry heaving.
The truth is that most of these "keto experts" confuse the therapeutic use of the keto diet to fight diseases like cancer (which does need to be strict) and keto advice for couch potatoes (which should still be strict) with advice for athletes and serious lifters (who need some metabolic flexibility).
So when you actually look beyond the macronutrient percentages and at the actual numbers of macros these athletes were eating, or care enough to read more of the study than the abstract, a much more sensible approach emerges.
Keto and Protein Misconceptions
During habitual diets leading up to a scientific trial-based study on the effects of ketosis on athletic performance, low-carb athletes were eating an average of 226 grams of fat, 82 grams of carbohydrate, and 139 grams of protein.
The protein might look low to you, but remember that these are endurance athletes we're talking about. The average bodyweight amongst the low-carb athletes was 152 pounds with an average lean body mass of 130 pounds.
So they were actually consuming 2.1 grams of protein per kilogram of bodyweight per day or 2.3 grams of protein per kilogram of lean body mass. That's 0.9 grams of protein per pound of bodyweight or 1.1 grams of protein per pound of lean body mass.
The latest research on the question of how much protein lifters need in order to build muscle and strength stated that 1.62 grams of protein per kilogram of bodyweight per day was the point of maximum benefit. These ketotic athletes were, on average, exceeding that number every day during their habitual diets leading up to the trial.
Wait a minute. These athletes were consuming 2.1 grams per kg of their bodyweight and they weren't getting kicked out of ketosis? You heard that correctly, keto queen.
Newsflash: A properly formulated ketogenic diet for athletes is NOT a low or moderate-protein diet. That's a complete myth that every non-athletic keto guru loves to perpetuate.
Protein is, in fact, the most important nutrient to get right on a keto diet for athletes. If it's too low, performance and strength goes out the window. If it's too high, you'll get kicked out of ketosis. Nevertheless, you can most certainly eat enough protein to build muscle on a keto diet while still enjoying the benefits of fat adaptation.
But What about Carbs?
So everyone knows that if you exceed 30 grams of carbs a day on the keto diet you'll get kicked out of ketosis and spark off a cascade of events inside of your body that'll eventually lead to you becoming obese, diabetic, and pooping in oversized diapers.
I wonder if these low-carb athletes realized that the study’s architect was trying to kill them when he had them eating an average of 82 grams of carbs a day? Or could it be that some people need more carbs than others, and that some athletes could eat more carbs than others and still remain in ketosis?
Actually, Volek and Phinney cover this in their book, The Art and Science of Low Carbohydrate Performance, albeit in a single short sentence. They explain that 50 grams of carbs or less per day is a good target to remain in ketosis, but that "...some people may need to stay under 30 grams while others can consume as much as 100 grams per day of total carbs and still remain in nutritional ketosis."
When they wrote this book, Volek and Phinney left the door open for overly zealous interpretations of what should be a highly variable and case dependent recommendation.
So let's put this in perspective. If you're a 60 year old overweight pre-diabetic man with minimal physical activity who wants to lose weight on keto, your limit of carbs is probably going to be closer to that 30 gram mark. If you're an athlete who's lifting weights, doing high intensity exercise, and carrying a decent amount of muscle, that number will probably be closer to 100 grams.
As Dr. Mike Roussell and Chris Shugart noted in their One Hundred Gram Carb Cure, 100 grams of carbs is actually a perfect number because it's "low enough that you'll be preferentially stoking your metabolic furnace with stored and dietary fats and not carbs. Also, most people won't experience any mental fogginess, crabbiness, or lack of energy that often accompany really low-carb diets."
It also leaves the door open for consuming enough vegetables and berry fruits to cover your micro-nutritional needs while leaving enough room for peri-workout carbs.
The Bottom Line
If you're an athlete doing a keto diet, the goal shouldn't be just to get your blood ketones up to a certain threshold. Rather, the goal should be to leverage increased ketone production for better performance while burning fat and building muscle. This means that your physical demands will require more protein and more carbs than your average keto dieter.
So while the "less than 30 grams of carbs a day" and low-protein approach should be avoided, you could still potentially benefit from fat adaptation with far less extreme measures than the popular version of the keto diet.
While the jury is still out on the benefits of a ketogenic diet over a higher carb diet for all athletes, ketosis for physical performance can be helpful for those doing ultra-endurance or low-intensity exercise meant to maintain health.
And let’s not forget the immense health benefits of eating a ketogenic diet, which just about every aspect of our lives overall, including physical performance.
Get bigger, stronger, faster, and more confident! DOMINATE your workouts!
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