A New Keto Diet Book's Simple Message: It's the Insulin

For 20 years, investigative journalist Gary Taubes has been turning the dogma of nutrition science upside down in a series of brilliantly detailed articles and books. Taubes' specialty is a form of historical excavation, painstakingly digging into the science and scientists who have created and sustained nearly a century's worth of failed conventional nutritional wisdom and policy.

Taubes is ideally suited to the role of unbiased medical outsider, for the simple fact that he does not come from biomedicine; he received a BS in applied physics from Harvard University and an MS in aerospace engineering from Stanford University, before obtaining a master's degree in journalism at Columbia University in 1981. He does not bring the misinformation baggage of a clinician, and he is not beholden to the National Institute of Health (NIH) or its committees for continuing grants or academic favors. He relies on no government or food industry ties and is able to deploy the full range of journalistic skills to study a complicated topic with as clear and critical eye as one can.

Those talents are on full display in his latest book, The Case for Keto: Rethinking Weight Control and the Science and Practice of Low-Carb/High-Fat Eating (Knopf, 2020), which offers yet more evidence that popular dietary misconceptions have led us down a perilous road. In his typically engaging style, Taubes illuminates our dietary relationship with fats and carbohydrates and what this may have to do with rising rates of obesity, diabetes, atherosclerosis, heart disease, cancer, and even dementia — conditions that in aggregate result in the deaths of about 75% of Americans (before COVID-19). In other words, his subject is a really big deal.

Myth-Busting Nutrition Science

To understand the importance of Taubes' work, let's play a quick game of "Truth, Myth, or It Depends" with 24 common dietary assumptions.

  • Worldwide, obesity is a human health challenge topped only by tobacco addiction and, currently, COVID-19: Truth

  • Consuming dietary animal fats and cholesterol in such foods as red meat, eggs, and butter is a key cause of coronary artery disease: Myth

  • Sugar is addictive: Myth (but it is strongly habituating)

  • Many different diets can lead to major weight loss: Truth (at least for every diet from Atkins to McDougall that shares a common final pathway)

  • Statements by US government agencies — especially the Department of Agriculture (USDA) and Department of Health and Human Services — regarding diet and nutrition are reliable: Myth (sadly, even the newest ones from the USDA)

  • Humans learn best from their own experiences: Truth (and a key to understanding the problem)

  • Many, even most, American physicians are poorly educated about nutrition: Truth (the weight control problems of vast numbers of their patients confirm that)

  • Consumption of fiber is a key component of obesity prevention: Myth (but it can be useful for gastrointestinal regularity)

  • A high LDL-C is more dangerous than established metabolic syndrome: Myth

  • The most important medical device is the bathroom scale: Truth (it should be used by all at the same time each day)

  • Three square meals a day is the basis for a sound healthy American diet: Myth (three meals a day are not necessary)

  • Breakfast is the most important meal of the day: It depends (on what and when the other meals are)

  • Intermittent daily fasting (17 hours) or an eating window (7 hours) is one excellent method of weight management: Truth

  • By the laws of physics, a calorie is a calorie: Truth

  • In human biochemistry, calories in must equal calories out for weight stability: Myth

  • Genes rule; some people are naturally lean, whereas others tend to fatten easily: Truth

  • The laws of thermodynamics overrule human endocrinology: It depends (on your genes)

  • Exercise is of critical value in the successful calorie-in/calorie-out concept of weight control: It depends (once again, on your genes)

  • Strong randomized clinical trial data underpin most nutrition recommendations: Myth (and this is unlikely to become true in your lifetime)

  • Strong published epidemiologic research supports most clinical nutrition policies: Myth (and sadly misleading to many people and organizations)

  • The best way to deal with obesity is to never become obese rather than try to lose weight: Truth

  • Obesity is treatable and weight loss is sustainable: Truth

  • A diet that includes ample amounts of whole grain is a good diet: Myth (but it is better than one with ample amounts of refined grain)

  • A diet full of fresh fruits and vegetables is a good diet: It depends (on which fruits and vegetables)

I suspect there is little agreement among readers in response to these 24 statements, which is exactly what makes Taubes' work so relevant.

The Case for Keto

Taubes' earlier books — Good Calories, Bad Calories (2007); Why We Get Fat: And What to Do About It (2010); and The Case Against Sugar (2017) — built compelling arguments on a well-researched foundation of published medical and scientific literature. In The Case for Keto, Taubes adds a new layer in drawing upon the voices and thoughts of some 100 physicians he's interviewed who adhere to "keto" thinking about their own lives and those of their patients.

Make no mistake, The Case for Keto is not just another diet book. Instead, Taubes offers a richly referenced, finely nuanced scientific treatise on the importance of endocrinology for weight control and the dominance of endocrine function over energy metabolism.

I count myself among those who grew up lean of body and have watched their own body mass index (BMI) go up and down over decades. To control those numbers, I've used the bathroom scale and waist tape measure regularly and adjusted the amount and type of food I take in and exercise I do.

Such an approach reinforces a strong belief that we are in charge — that our volitional behavior controls our BMI. It can be difficult to comprehend why everybody can't subscribe to that traditional calorie-in/calorie-out model. In considering the obesity epidemic, I erroneously extrapolated my own experience as a naturally lean person to others.

Yet many of the physicians Taubes has interviewed for this book are certain that stringent application of the intelligent voluntary control of calories simply does not work for many people. Virtually all humans are capable of fattening, but for some, fattening is easy and seems inescapable. For them, physics and chemistry do not apply. The answer is endocrinology, and specifically insulin levels.

Where We Went Wrong

Most physicians in the United States have had little education about nutrition and, since about 1980, what we have been taught about "healthy foods" (not counting vitamin deficiencies, such as scurvy, beriberi, and pellagra) has been mostly wrong.

What happened shortly after 1980, when the worldwide obesity epidemic began? The gene pool did not change. Did epigenetics change the energy metabolism of hundreds of millions of people?

No. The NIH and lots of confreres decided that animal fat was bad, that it caused atherosclerosis, and that its intake should be greatly reduced. They said that the anticipated increased intake of carbohydrates would be benign; after all, fat delivers 9 calories per gram while carbohydrates only deliver 4.

Since then, countless dietary approaches have been suggested to counteract the troubling obesity trend: vegetarian, vegan, Atkins, Mediterranean, Paleo, keto, 16-8 intermittent fasting. What they all have in common is a prohibition on sugary drinks/foods, highly processed foods, and highly refined grains. Blood sugar remains low, as do insulin levels. Insulin loads fat into fat cells and locks it up there; ergo, fat weight gain occurs.

Taubes admits that some humans seem predestined to remain "lean," and they may well be able to abide by the physics/mathematics approach of calories-in/ calories-out. But huge numbers of humans are destined to fatten unless their insulin levels are kept very low. The drive to lower fat and cholesterol from 1980 turned the switch that opened the floodgates of obesity. What we now recognize as a public health debacle led to the new, mostly unrecognized, plague of elevated blood insulin.

Your body will preferentially burn carbs for energy if given a choice. The way to not be fat is to burn fat for energy, either the fat you've stored or what you've ingested. The best way to do that is to not eat carbs, so that you must burn fat. Keep blood insulin low to prevent fat cells from storing and retaining fat. Intermittent daily fasting — that is, 17 consecutive hours of not eating followed by a daily 7-hour period of eating all you want — is a sustainable style. Either skip breakfast or skip dinner. Do not skip lunch, unless you prefer to eat only one large meal a day.

When I Went 'Keto Light'

I like to stop eating at about 7 PM, on a day during which I've consumed a high-protein, high-fat brunch of eggs and bacon or sausage, plus low-sugar fruits and vegetables, such as berries, tomatoes, avocado, or olives, at about noon. That provides many hours for the burning of fat for essential energy. Of course, I try to eat absolutely no added sucrose, sugary drinks or snacks, refined carbohydrates, ultra-processed foods, or processed food with added sugar.

I would call this approach "keto-light," because I do not attempt to achieve ketosis and my evening meal can include vegetables grown under the ground as well as above ground, and some grain in the form of dense, dark bread baked with berries and nuts, plus lots of butter.

I get on the same scale unclothed at the same time every day. And I am guided by the number. Without that basic act, weight control is a lost cause.

Doing this over the past 6 months has allowed me to lose 10 pounds and achieve my target weight while practicing a high but unchanged level of exercise. My Fitbit tells me that I average 6000-7000 daily steps (the same as 2015-2019), nightly sleep of 7.5 hours, and a resting heart rate of 64 beats/min.

The Same Old Mistakes

As I finished writing this book review, along came the most recent report from the Centers for Disease Control and Prevention that 42% of US adults have obesity and over 73% have either obesity or overweight. Yet another public health emergency.

Then, here arrive the USDA's Dietary Guidelines for 2020-2025. What a mess. It still permits lots of sugar, including added sugar. Why? It talks about "healthy foods." What are those?

As a devotee of evidence-based medicine, I place a premium value on long-term, large-scale, community-based and representative randomized, blinded clinical trials with strong statistical power. No published studies have tested the hypotheses put forth in Taubes' series of books. And there probably won't be any in the lifetimes of most of the people reading this book review. Such trials take too long, are too difficult to perform, and are too expensive. But the real-world experience and evidence seem irrefutable to me and provide plenty to act upon, considering the personal and public health stakes.

With top-tier evidence-based medicine off the table, we must resort to lower levels of evidence. Much of the middle tier is epidemiology, and John Ioannidis has pretty much trashed that whole field of inquiry when it comes to clinical nutrition.

So, one "advances" to the lowest level of evidence: the anecdote, also known as the clinical trial with "an N of 1." It turns out that this may provide the best evidence for any one individual, and if that individual is a physician, they may apply the findings of their own experiment to their patients and follow them carefully. And that, dear reader, is what this book does. It reports what scores of physicians recount as their own personal and practice experiences with thousands of "N of 1" trials.

In addition to all of us, the organizations whose members have the most to gain (or lose) by acting upon the current evidence include the American Medical Association and all of its representative specialty societies, the American Heart Association, the American Diabetes Association, the American Cancer Society, the American College of Cardiology, and countless others. What many of these societies have continually told us is a "healthy diet" has clearly not made us healthy. This should make it relatively self-evident that it is time for a fresh start.

Reading all four of Taubes' books, preferably in chronological order, or simply his latest work is a great place to begin the process of expanding your knowledge, challenging and perhaps modifying your attitude, potentially revising your personal and medical practice behavior, and improving your outcomes.

If you want a brief survey of this work, you can also click on my 2018 Medscape columns It's Not the Fat That Makes Us Unhealthy and Could It Be the Sugar?, or listen to the lecture Taubes gave that same year on behalf of my institute.

But for the particularly time-strapped, let me give you the skinny (so to speak) on the keto diet: Avoid using carbohydrates for your energy; use fat — stored as well as recently eaten. And keep your blood insulin low!

Despite what you may have heard, it's really that simple.

George Lundberg, MD, is contributing editor at Cancer Commons, president of the Lundberg Institute, executive advisor at Cureus, and a clinical professor of pathology at Northwestern University. Previously, he served as editor-in-chief of JAMA (including 10 specialty journals), American Medical News, and Medscape.

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