The ketogenic diet has increased in popularity recently — from a small niche following to the mainstream in just a few years. With more attention, though, has come more criticism.
“It’s not safe or sustainable,” some have said. “It’s bad for building muscle and it’s too restrictive,” others assert. I have heard all of these statements and more.
Within the CrossFit community, the criticism has been especially strong. Many argue that CrossFit is too “glycolytic” (carb dependent) for keto to be feasible. I’d like to pose a counter-argument: not only is keto feasible for performing your daily WOD, it may actually be better than a typical high carbohydrate diet. To illuminate this point, I want to review some of the science on the subject along with the impact of the ketogenic diet on everyday CrossFit and strength-based athletes.
Importantly, CrossFit HQ supports the ketogenic diet and has published many positive studies on keto in their daily email and made “Nutrition Network Professional Training in LCHF/Ketogenic Nutrition” a preferred course. A small disclaimer, I am a Certified Ketogenic Health Coach, not a nutritionist or a doctor. I have been testing the keto diet with CrossFit for over a year now and have been very happy with the results, including a better body composition, good performance and excellent blood markers.
What is the ketogenic diet (the short version)?
The ketogenic diet is the only diet in existence that fundamentally transforms the way your metabolism operates. All other diets rely mostly on glucose as a fuel source; whereas keto actually relies on fat to energize you, both from the fat you eat and your body fat. As you metabolize fat, ketone bodies are released — this is where the magic lies. Ketone bodies have numerous healing effects on the body, including weight loss, lowered blood sugar, improved cholesterol and triglycerides, reduced risk of heart disease, increased cognitive performance, improved neural functioning, and they can even serve as an adjuvant cancer treatment. The two ways to get into “ketosis” are to fast for an extended period of time, or eat a diet high in fat, with these approximate macros: 60-80% fat, 15-25% protein, and 5-10% carbohydrates. This ratio will vary depending on your goals, activity level, and individual metabolism.
“The ketogenic diet is the only diet in existence that fundamentally transforms the way your metabolism operates. All other diets rely mostly on glucose as a fuel source; whereas keto actually relies on fat to energize you, both from the fat you eat and your body fat.”
Why do keto and CrossFit work so well together?
First, there have been two studies performed specifically on CrossFit athletes following a ketogenic diet. What we learned in the first study is that the athletes following the keto diet actually lost much more body fat than the control group who followed a typical high carb diet, and there was no significant difference in the performance metrics of 1RM back squat, 400m run time, and VO2max. In other words, the keto athletes achieved a better body composition and did not lose any ground in performance.
In the second study, a group of individuals undertook a four-week ketogenic diet to see how it impacted their exercise metabolism. The results show that the keto diet caused athletes to burn a higher percentage of fat for fuel at higher exercise intensities. This is a big deal because it means that these athletes were relying on their endless supplies of fat for energy, even at exercise intensities up to 80% of VO2max. Just for context, CrossFit workouts generally fall in the 49-64% of VO2max range. By relying more on fat at higher intensities, the athletes were saving their limited glycogen stores for use only on those max effort bursts and burned more body fat at the same time.
How can someone eating almost no carbs perform high intensity exercise fueled by glucose?
The body is a miraculous machine that can adapt to many situations, including a shortage of carbohydrates. Once someone becomes fat-adapted, meaning they can burn and utilize fats efficiently (this can take 2-4 weeks of following the keto diet consistently), their body also becomes extremely good at making glucose internally from ingested protein, fat, and even lactic acid. This concept is called gluconeogenesis. A keto athlete can actually replenish their glycogen from fat and protein just as fast as an athlete who is eating a carb-based diet. This idea is revolutionary to many, but it is the key reason why keto works and works especially well for CrossFit.
What about building strength and muscle mass?
Strength is a huge component of CrossFit, and people generally believe it is not compatible with keto. The facts show, however, that you can gain lean mass and strength on a keto diet to a similar degree as you can on a carb-based diet. An interesting side note is that keto can actually drastically increase testosterone, which is a critical hormone for athletic performance and overall health.
In another study, professional Olympic lifters and powerlifters ate either a high carb diet or a keto diet. The keto athletes saw the same performance increases as the high carb athletes, but the keto athletes actually saw a much better body composition, with a large loss of fat. So, like the keto and CrossFit studies, strength athletes experienced improvements in their body composition, with no negative side-effects for strength and performance.
Can a ketogenic diet improve recovery too?
Inflammation can be a huge problem for the typical CrossFit athlete, as the demands of the sport are so intense. One key to adequate recovery is a quick reduction in the inflammatory response brought on by exercise. Ketone bodies themselves have been found to both reduce oxidative stress, reduce overall inflammation, and can even enhance endurance exercise fatigue recovery.
I have covered a fair amount of ground here, but really, I’ve only scratched the surface. I hope this has at least convinced you to have a more open mind about keto and CrossFit, and even perhaps give the keto diet a fair shot. It is time to drop the old stigma that only carbs can fuel intense exercise. My personal experience has revealed that by following the keto diet through an extremely well-implemented plan, you can begin to see benefits to body composition, metabolic efficiency, strength, Olympic lifting and even reduce your overall inflammation, within a month.
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