Article by Mark Sisson
Now that keto has achieved widespread popularity and even acceptance in mainstream health circles, the nuances of best practices are being examined closely. Most are of the mind that there is no one size fits all approach and that testing and re-testing is essential to dial in what works best for you. No single issue has been more scrutinized than the role of carbohydrates in one’s keto strategy. Let’s discuss the optimal carb intake range for a keto enthusiast, including variation based on your individual metabolic and peak performance goals. While it’s undisputed that devoted carb restriction to the tune of 50 grams per day or less is the fundamental driver of ketone production in the liver and reaching the official status of nutritional ketosis, a long-term strategy might entail a bit more flexibility in your carbohydrate intake as you pursue a keto lifestyle in general.
If you are immersed in a devoted period of nutritional ketosis, experts agree that you must stay below 50 grams of gross carbohydrate intake per day. You may have heard about net carbs, which subtract the grams of fiber in a particular food from the gross carbohydrate content to deliver a net carb figure. While this is a relevant calculation for things like high fiber vegetables, many packaged and processed foods tout a low net carbohydrate value that can be inaccurate; that is, your body may metabolize the so-called fiber as carbohydrate, rendering the “low net carb” snack food as a sugar bomb.
The Keto Reset Diet recommends tracking gross carbs with the exception of leafy green vegetables and avocados. These foods might have so few net carbs that you can essentially count them as zero toward your keto goals. Indeed, a liberal consumption of nutritious vegetables is essential during even the most hard-core keto efforts. Veggies in the leafy green family, cruciferous family, and other colorful, high fiber offerings grown above the ground deliver minimal net carbohydrates, tons of important antioxidants and micronutrients, and also support a healthy gut microbiome. Since ketosis is such a fragile state, selectivity is warranted when it comes to starchy vegetables grown in the ground, such as sweet potatoes, carrots, rutabaga, squash, zucchini and so forth.
There are numerous other low-carb, nutrient-dense foods where the incidental carb count will gently climb you up toward 50 grams if you are keeping track. So if you put together abundant intake of high fiber, above ground veggies (leafy greens, cruciferous, etc.), assorted other veggies, and incidental carbs from nuts, seeds, and their butters, coconut products, high cacao percentage dark chocolate, and perhaps a bit of fresh berries, you are likely going to land safely under 50 grams, but you’ll certainly default to half of that total when these healthy foods are in your diet. Hence, there is no good reason to shoot for zero carb consumption during keto. Nutrition—and enjoyment of life—is important too!
With that, I think we have established a sensible minimum carb intake of, say, 20 grams per day as you consume healthy, whole foods with the emphasis on fresh produce. By the way, if you are inactive, the upper limit of carb intake for nutritional ketosis is not 50 grams per day, but rather 20 grams. Key take home point here: make sure you stay active! Even if it’s just walking the dog or taking the stairs instead of the elevator, having a decent baseline activity level is a strong promoter of keto success.
If you are aggressively trying to reduce excess body fat, recover from metabolic damage caused by yo-yo dieting, or reduce your risk of cognitive or diet-related diseases with a devoted keto stint, you may find best results come from consuming a minimum carb level for a sustained period. Respected experts like Dr. Phil Maffetone and Nora Gedgaudas advocate for staying in nutritional ketosis indefinitely, especially for the aforementioned high need populations.
On the flip side, those with optimal body fat levels, favorable blood values and ambitious fitness regimens might allow for a wider range of carbohydrate intake as they pursue a keto lifestyle but not necessarily strict nutritional ketosis. I call this wider range of carbohydrate intake the “keto zone” and believe that for metabolically fit individuals, there is no significant difference in health benefits from ranging across the zone in either a regimented manner (with reefed periods, for example) or spontaneous manner (with birthday parties or cruises, for example!). Regarding the upper end of the keto zone, I talk in The Primal Blueprint about a daily carb intake limit of 150 grams per day that equates with an ancestral-style eating pattern. You are still very low carb in comparison to a grain-based Standard American Diet, but a little more flexible than a keto enthusiast: abundant with veggies, a little more liberal with fruits and incidental carbs from the aforementioned sources, and perhaps also including regular consumption of nutrient-dense high carb foods such as sweet potatoes, quinoa, wild rice, and legumes like hummus. Beyond that, there may be a bit more tolerance for occasional non-primal indulgences: small corn tortillas for your fish tacos, a few handfuls of popcorn at the movies, a few extra squares of dark chocolate after dinner, regular dosing of your water mug with kombucha, and so forth.
If you are inclined to split hairs about carb intake, or challenge the assumption that eating in the keto zone for the metabolically fit is just as good as hard-core keto, this is where personal experiment should rise to the forefront. Dr. Phil Maffetone’s two-week test for carbohydrate intolerance allows you to gradually re-introduce excluded high carb foods and be vigilant for any adverse effects. Remember that the existing science and protocols for keto emanate from the medical world. There is still precious little data on keto from fit populations, and there are surprisingly few definitive conclusions about anything keto-related from the most respected scientists. For hard training athletes in particular, it appears that the 50 gram per day upper limit can be relaxed and that you can experience the benefits of nutritional ketosis with significantly higher carb intake due to the high calorie burning, frequent glycogen depleting metabolic patterns. These benefits include the highly touted autophagy (the natural internal cellular detoxification process) benefits that accrue from fasting and ketogenic eating. Dr. Tommy Wood of NourishBalanceThrive.com suggests that the stimulus of glycogen depleting workouts on cellular mitochondria is similar to what happens when you are fasting. In both cases, you are putting a hormetic stress on your cells, and they respond by becoming more efficient at processing oxygen and energy and protecting against free radical damage.
I have really appreciated how Ben Greenfield carefully chronicles his experience with keto style eating paired with rigorous training for extreme endurance events, obstacle course racing, or other crazy feats. It’s clear that one can succeed with ambitious endurance goals even while adhering to a traditionally strict ketogenic diet if they do it correctly. It’s also been shown by elite athletes that cycling in and out of strict keto is an effective strategy. Listen to Zach Bitter on the Primal Endurance Podcast talk about how he gets stricter with keto during offseason or buildup training phases. During the competitive season and during actual ultramarathon races, he allows for higher carb intake commensurate with the increased intensity of his key workout and racing efforts.
One thing to emphasize is that the benefits of grooving along in the keto zone of 20 to 150 grams a day is best enjoyed when you have done the devoted work to escape from carbohydrate dependency and become fat- and keto-adapted. If you are metabolically unfit—frustrated with your inability to reduce excess body fat, have a triglyceride-to-HDL ratio that is higher than 2:1, have a history of metabolic damage, autoimmune conditions or other unpleasant metabolic “issues,” or have difficulty skipping meals and stabilizing appetite, mood, energy output, and cognitive function, you face a different set of decision making steps than someone with metabolic flexibility. If you are struggling, a deep dive into keto can be an absolutely transformative experience, but you have to do it correctly.
Many ill-prepared keto enthusiasts jump into the game on the heels of a grain-based, high carb, high insulin producing diet. They suck at burning stored body fat, then they abruptly cut off their longtime preferred source of energy that is dietary carbohydrate. What happens when a sugar-burner goes keto is that the fight or flight response kicks in to meet their massive glucose requirements by breaking down lean muscle tissue. This leads to fatigue, burnout, and a change in hormonal patterns that cause an increase in both appetite and fat storage.
In my New York Times bestselling book, The Keto Reset Diet (released in October 2017), I detail a methodical, step-by-step process to ditch carbohydrate dependency and become fat adapted, not only through dietary modification but by also paying close attention to complementary exercise, sleep and stress management habits. This “21-Day Metabolism Reset,” detailed in the book as the first phase of the keto journey, boosts your metabolic flexibility, setting you up for a focused period of nutritional ketosis that will avail you further metabolic flexibility benefits. To make sure you are ready, you do some fine-tuning in the form of fasted mornings, carefully tracking your progress and until you confirm that you can operate comfortably without food until noon. This means not feeling hungry or tired, not having to call upon fragile willpower to skip meals, and even being able to exercise and perform peak cognitive tasks without a meal.
After passing a midterm exam of sorts relating to your subjective evaluations of metabolic fitness, you then make a 6-week commitment to nutritional ketosis, with a hard limit of 50 grams of carbs per day (only 20 grams if you are inactive—which you shouldn’t be!). Once you complete your 6-week keto stint, you have developed an exceptional level of metabolic fitness, which you can leverage into an assortment of long-term strategies to discover what will work best for you. Some, especially those coming from metabolic damage or wishing to reduce excess body fat, might benefit from staying in strict keto for months or even years. Those with ambitious fitness goals, optimal body fat levels, and excellent blood work absent of metabolic risk factors, might not need to worry about ever dipping below the keto cutoff, and can enjoy maximum energy and peak performance floating around in the upper area of the keto zone.
This is where personal preference and intuition become the most important operative variables. Of course, you have to nail the basic principles and stay away from the caramel frappucinos, Jamba Juice smoothies, and deep fried fish sticks, and build the metabolic flexibility that enables you to pursue a flexible approach. You also have to respect your personality attributes and proceed in a manner that will feel natural and easy to maintain. For example, I’m not big on regimentation or obsessive macronutrient counting. I also have fluctuating workday and travel patterns such that my average day of eating is difficult to describe because it varies so much. If I were to test myself (which I’ve done over time for book research, but not as a daily habit), I’d be drifting into and out of nutritional ketosis constantly, and without really noticing it in any way.
While I allow my carb intake to fluctuate across the complete keto zone, I don’t engage in any strategic carbohydrate refeeds. On the other hand, I will occasionally engage in purposeful ketogenic eating periods lasting from three to six weeks. I believe a devoted annual keto period lasting six weeks, ideally in the winter, is a great idea for most everyone. I also like the idea of doing mini-keto periods of around three weeks a few other times a year, and will probably follow a pattern like this for the rest of my life.
There has been some debate about the worthiness of refeeds as a component of a keto lifestyle. I would like to share an excerpt from The Keto Reset Diet on this topic to give you some food for thought on the topic.
Excerpt: The Keto Reset Diet
Refeeding is a popular strategy in the low-carb and keto community to help preserve insulin sensitivity in the face of prolonged suppression of insulin through keto eating. Refeeding strategies are also seen as a way to reduce the psychological stress of adhering to rigid macronutrient standards by allowing for what are often called “cheat days.” This is a term I despise because it implies that your normal dietary patterns are somehow unpleasant. I’d rather your approach to keto be motivated by a deep appreciation for the most satisfying, nutrient-dense foods on the planet, and that instead of longing for grain and sugar treats on occasional cheat days, you habituate away from nutrient-devoid modern foods by replacing them with foods that are deeply nourishing.
The rationale for refeeding is that if you maintain low insulin levels for a long time, your cells may become somewhat resistant to insulin’s signals because they don’t have to deal with significant amounts of insulin-like a muscle atrophying from lack of use. Consequently, a refeed is conducted to balance prolonged periods of carb restriction with purposeful days or weekends of high carbohydrate intake. This would prompt a heavy insulin response, wake up the receptor sites, and hone insulin sensitivity in the process. A refeed also allows for some dietary indulgences that aren’t happening when one is trying to adhere to keto guidelines. As stated previously, it’s possible that refeeding can be problematic for certain individuals, and that a gradual reintroduction of higher-than-keto carbohydrate intake is the best strategy.
That said, there are simply and absolutely no health objections to long-term keto (remember, that’s our predominant ancestral dietary pattern). Indeed, indefinite keto can be the healthiest strategy for many individuals, especially those with metabolic damage. What’s more, Luis Villasenor—going strong and getting stronger in keto for 16 years and counting—asserts that the complaint of developing insulin resistance from long-term keto is likely due to confusing pathological insulin resistance with physiological insulin resistance. With the former—the traditional disease definition— chronic overproduction desensitizes cell receptor sites, setting the stage for type-2 diabetes. With the physiological insulin resistance that occurs in highly fat- and keto-adapted individuals, fatty acids accumulate in muscles as the primary fuel source, causing receptor sites to turn away glucose. This can cause glucose to occasionally rise in the bloodstream, giving the appearance of pathological insulin resistance, but without any disease risk or adverse health consequences. Referencing earlier discussions about athletes having low ketone numbers and occasional high glucose numbers, physiological insulin resistance could provide a good explanation.
Thanks for your interest in keto, hopefully you have some good insights that will help you devise an effective custom strategy. Check out KetoReset.com for details about the book, and information about the upcoming online multimedia educational course.