A little appreciated (but important) fact: for most of human history, the average person would have been regularly exposed to ketosis. This was mostly light and transient, sometimes more protracted, but they were never far from a mildly ketogenic state. Food wasn’t always a sure thing, after all, and carbs weren’t necessarily readily available year-round. Ketosis was normal, it was frequent, and it was beneficial, even life-saving.
Today, few people achieve ketosis without intentionally fasting or following a ketogenic diet. The latter refers to any very low-carb diet—low enough that your liver churns out ketones that your cells can use for energy in place of glucose. It may feel like keto exploded into popularity out of nowhere, but doctors have actually been prescribing therapeutic keto diets to treat epilepsy for more than a century. Today, keto is popular mostly as a weight-loss diet, but that’s only the tip of the iceberg when it comes to the benefits a keto diet has to offer.
That’s because keto diets have two things going for them: the carbohydrate restriction and the resulting ketones. Each profoundly affects health and longevity, beyond halting seizures and helping people fit into smaller jeans. I’ve been talking about keto since the early days of the Primal Blueprint because I firmly believe that everyone should spend time in a state of ketosis.
Here are some of the reasons why.
Why Go Keto? The Big Picture
The number one reason I recommend that everyone try keto is for metabolic flexibility. To put it bluntly, if you want to be metabolically healthy, you must be metabolically flexible. Metabolic flexibility, you may recall, is your cells’ ability to use any available substrate—glucose, fat, or ketones—for energy on an on-demand basis. It’s the opposite of carbohydrate dependency, the metabolic state that characterizes the vast majority of the population today.
Keto diets upregulate your cells’ ability to burn ketones, obviously, but they also make you more fat-adapted. And being able to metabolize fatty acids efficiently is important whether you’re keto or eating a “regular Primal” pattern.
There are other things that keto does uniquely well compared to other types of diets, namely lowering blood glucose, insulin, and inflammation. Hyperglycemia, hyperinsulinemia, and chronic inflammation are the triumvirate of doom when it comes to chronic disease. I can’t think of a single chronic disease of any kind—metabolic, autoimmune, neurodegenerative, cancer—that doesn’t have one, if not all three, as a contributing factor.
It’s obvious why seriously restricting carb intake would reduce blood sugar and insulin secretion, in turn reducing inflammatory markers.1 Keto diets also trigger more complex downstream biochemical processes that account for many of their beneficial effects. For example, keto modulates the action of a critical enzyme called AMPK that is involved in cellular energy regulation—improving glucose uptake by cells, improving insulin sensitivity, and decreasing inflammation.2 The ketone body beta-hydroxybutyrate has direct anti-inflammatory effects.3
In short, with keto diets, you reap the benefits of NOT eating too many carbs plus a host of other benefits that are specifically due to being ketotic.
Benefits of the Keto Diet
The Keto Diet for Treatment of Major Disease States
The ketogenic diet remains the only thing with the consistent ability to prevent epileptic seizures. We have better medicines than doctors did a hundred years ago, but not everyone responds to them. Whether it’s Thai kids with intractable epilepsy,4 Scandinavian kids with therapy-resistant epilepsy,5 or adults with refractory epilepsy,6 ketogenic diets just work.
Ketosis improves epilepsy via several mechanisms.
It increases conversion of glutamate into glutamine into GABA, reducing neuronal excitability.7
It increases antioxidant status in the neuronal mitochondria, improving their function.
It reduces free radical formation in neurons, a likely cause of seizures.8
It provides an alternate fuel to brain neurons that may be dysfunctionally metabolizing glucose.9
These effects on neuronal function and health, along with the ability of aging or degenerating brains to accept and utilize ketone bodies, also have implications for other brain conditions, like Parkinson’s,10Alzheimer’s,11 and bipolar disorder.12Ketogenic diets aren’t just beneficial for brain disorders, though. People with mild cognitive impairment and even generally healthy folks can enjoy cognitive benefits like improved memory, mental clarity, increased focus, and positive mood, to name a few.
And the impact of keto extends well beyond the brain. For example…
A Spanish ketogenic diet (keto with wine, basically) reversed metabolic syndrome and improved health markers of non-alcoholic fatty liver disease. Over 92 percent of subjects improved their liver health; 21 percent resolved liver disease entirely.13
Keto diets are poised to be the next big tool in preventing and treating cancer. Keto diets significantly reduce circulating glucose—the preferred fuel of most types of cancer—inhibiting the ability of cancer cells to proliferate. Although research results are still very preliminary, it is suggestive that keto diets can be used to augment (not replace) traditional cancer therapies in many cases. In cancer patients, a keto diet also preserves lean mass and causes fat loss.14
Ketogenic diets may improve symptoms of PCOS, which is strongly related to insulin resistance.15
The Keto Diet for Physical Performance
Being keto-adapted has several advantages for anyone interested in physical performance.
It increases energy efficiency. At any given intensity, a keto-adapted athlete burns more fat and less glycogen than a sugar-burning athlete. Long-term elite keto athletes can burn up to 2.3 times more fat at peak oxidation and 59 percent more fat overall than non-keto athletes, and they do it at higher intensities. They remain in the predominantly fat-burning zone at 70 percent (or higher!16) of VO2max, whereas non-keto athletes switch over from primarily fat burning to a spike in sugar-burning at 55 percent VO2max.17
It spares glycogen. Glycogen is high-octane fuel for intense efforts. We store it in the muscles and liver, but only about 2400 calories worth—enough for a couple hours of intense activity at most. Once it’s gone, we have to carb up to replenish it, lest we hit the dreaded wall. Keto-adaptation allows us to do more work using fat and ketones for fuel, thereby saving glycogen for when we really need it. Since even the leanest among us carry tens of thousands of calories of body fat, our energy stores become virtually limitless on a ketogenic diet.
It builds mitochondria. Mitochondria are the power plants of our cells, transforming incoming nutrients into ATP. The more mitochondria we have, the more energy we can utilize and extract from the food we eat—and the more performance we can wring out of our bodies. Ketosis places new demands on our mitochondria, who adapt to the new energy environment by increasing in number.
The Keto Diet for Fat Loss
Ketosis isn’t “magic”—it doesn’t melt body fat away. Instead, it works for many of the same reasons a standard low-carb Primal way of eating works: by reducing insulin, increasing mobilization of stored body fat, and decreasing appetite.
Ketosis suppressing appetite may be the most important feature. The overriding drive to eat more food is the biggest impediment to weight loss, and it’s the reason why most diets fail. When people attempt to eat less food despite wanting more, they butt up against their own physiology. Few win that battle. Ketogenic dieting avoids this issue altogether, suppressing the increase in hunger hormones that normally occurs after weight loss.18
Many diets work in the short term and fail in the long run. Weight loss isn’t worth anything if you can’t keep it off. Ketogenic diets appear to be good for long-term maintenance of weight loss, at least compared to low-fat diets.19
How to Go Keto the Right Way
The real benefits of keto come from doing keto the right way. Almost no one reading this needs to follow a strict therapeutic diet of the type usually prescribed to epileptic patients, typically involve exceedingly high fat and low protein.
For most of us, keto works best when we prioritize nutrient density, healthy fats, and a good amount of protein—a Primal way of eating but with fewer carbs. My books The Keto Reset Diet and Keto for Life go into detail about how to implement this way of eating, or start with my Definitive Guide to Keto.
The point I want to make clear is that keto diets are beneficial in ways that other diets aren’t by virtue of the ketones and the carb restriction, but you don’t need to be keto forever to reap the rewards. Dipping into ketosis for four to six weeks at a time, a few times a year, is sufficient. If you discover that you feel best in ketosis, then you can absolutely stay there. For everyone else, it can be a periodic thing.
Just don’t pass up the opportunity to achieve ultimate metabolic flexibility!
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.