It’s been almost 50 years since the original edition of the Atkins diet was published, and in recent years the ketogenic diet—which Atkins was the first to popularize—is enjoying an unprecedented amount of attention. (As I write this column, I’m sitting in a stateroom on a cruise ship—I’m presenting two talks on the 11th annual Low Carb and Keto cruise, which continues to sell out every year.)

Keto diets—as they’ve come to be known—have always had a reputation for weight loss. But keto diets are also the ultimate tool when it comes to lowering insulin resistance, and in recent years research is exploding on the diet’s other wide-ranging health benefits. Everyone’s talking “keto” and the buzzword is turning up on a crop of products and programs which may—or may not—have a lot to do with ketosis itself. So it’s worth spending a few minutes discussing what, exactly, a “keto” diet is.

When the first edition of Dr. Atkins book, Dr. Atkins’ New Diet Revolution, came out in 1972, one of the central features of the diet was nutritional ketosis. Atkins actually called ketosis " …one of life's charmed gifts. It's as delightful as sex and sunshine, and it has fewer drawbacks than either of them." Hyperbole? Maybe a little. Meanwhile, advocating for ketosis got Atkins in a ton of hot water with the medical establishment who believed that ketosis was only something that happens in starvation (untrue). Furthermore, many doctors thought “nutritional ketosis” was the same as a life-threatening condition called diabetic ketoacidosis (also untrue). Diabetic ketoacidosis is as different from nutritional ketosis as dolphin (the edible fish) is from Flipper.

But times have changed. Ketogenic diets are an accepted treatment for childhood epilepsy and are used at hospitals (such as Johns Hopkins) around the country. Ketogenic diets are being used successfully for weight loss, notably at the Duke University clinic run by Eric Westman, M.D. And at the University of South Florida, professor Dominick D’Agostino, Ph.D., and his team have been working with the Navy to research the performance-enhancing effects of ketogenic diets on Navy Seals. Professor Jeff Volek, Ph.D., R.D.,—one of the most credible and respected scientists doing peer-reviewed research on the keto diet—has worked with ultra-marathoners and tri-athletes who are on the keto diet and swear it has improved their performance.

So what exactly is a ketogenic diet?

A ketogenic diet is a diet with so little carbohydrate in it that the body is forced to use fat (instead of sugar) as its primary fuel source. Clearly this has advantages for weight loss, but it apparently has other advantages as well. Since ketogenic diets are by definition high in fat (and moderate in protein), they don’t jack blood sugar up, and therefore the demand on the body for insulin is greatly reduced. When insulin is no longer elevated all the time—the way it frequently is on a high-carb diet—the cells begin to regain their sensitivity to insulin and insulin resistance begins to fade. As everyone who reads my columns knows, insulin resistance is a factor in a baker’s dozen of degenerative diseases, so anything that increases insulin sensitivity (reducing insulin resistance) is a pretty terrific thing for health and longevity.

Ketones—also known as ketone bodies—are produced as a by-product of fat-burning. And they are a terrific fuel for the heart, the muscles and the brain. And let’s remember that cancer cells thrive on sugar—it’s really their only fuel.(1) So when you reduce sugar in the diet (and the bloodstream), you’re essentially depriving cancer cells of the fuel they need to survive and spread. Ketogenic diets are now being proposed as an adjunctive cancer therapy (2). Anecdotally, some well-known people in the health and fitness space—namely superstar Hollywood trainer Vinnie Tortorich-- have credited a ketogenic diet with keeping their cancer in remission. And noted researcher (and TED lecturer) Terry Wahls, M.D., has pioneered ketogenic diets for multiple sclerosis, plus she is currently conducting trials of her particular form of the diet—known as the Wahls protocol—for MS patients.

To summarize, the ketogenic diet is essentially “very low carbohydrate high fat diet” (abbreviated LCHF)--one that produces a state known as nutritional ketosis. People who follow keto diets usually monitor their ketone levels with devices that allow them to measure ketones in the blood, the urine, or, more recently, through the breath. In their excellent book, The Art And Science Of Low Carb Living, Professors Jeff Volek and Stephen Phinney, M.D., Ph.D., define “light nutritional ketosis” as a ketone level of between .05 – 1.0 mmol/L, and “optimal ketosis” between 1.0-3.0 mmol/L.

My personal opinion is that ketosis is a wonderful nutritional intervention for a variety of conditions, but that one doesn’t have to be in nutritional ketosis 24/7 to get the benefits of the diet. You can—as many people do—go “keto” a few times a year, as a metabolic reset. (My friend, the philosopher, personal trainer and naturopathic physician Jade Teta, N.D., advocates this approach.) It’s also possible to “flirt with ketosis”, just by eating a low-carb high-fat diet (which is what I do, at least most of the time). The diet may not always put you in nutritional ketosis, but it will almost certainly have a positive effect on your blood sugar and insulin.

There are many ways to do keto, and many variations for specific groups (i.e. female athletes). My own program, The Metabolic Factor, is a version of keto known as “carb cycling,” wherein you stay on a very low high fat diet but one that is punctuated with a number of strategically placed “carb feasts.” A great guide to anyone wanting to delve into keto is the excellent book Keto Clarity by low-carb guru Jimmy Moore and Dr. Eric Westman of Duke University.

Remember, too, that you can get into ketosis using junky, processed fats (and junky processed meat) or you can get into ketosis the healthy way, using really high-quality fats like Malaysian red palm oil (which is sustainable, by the way), grass-fed butter, ghee, avocado oil, coconut oil (my favorite is Barlean’s), and extra-virgin olive oil (I like Cobram Estates, which is the greatest bargain in the world at Sprouts at under 10 bucks). Stay away from seed oils like corn, soybean, canola, “vegetable” oil and other oils that are extremely high in pro-inflammatory omega-6s.
(Adapted from the forthcoming book, The Most Effective Ways to Live Longer: Revised and Updated Edition (Fairwinds Press, 2019)

Jonny Bowden, “the Nutrition Myth Buster,” is a board-certified nutritionist and thejonny bowden best-selling author of 15 books including The Great Cholesterol Myth, Living Low Carb, the 150 Healthiest Foods On Earth and Smart Fat. To learn more about healthy living, motivation and nutrition, visit

Note: The statements presented in this column should not be considered medical advice or a way to diagnose or treat any disease or illness. Dietary supplements do not treat, cure or prevent any disease. Always seek the advice of a medical professional before altering your daily dietary regimen. The opinions presented here are those of the writer.