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THE LOW-CARB FRAUD

It’s no secret that Americans struggle with weight loss. Since 1980, when the rise in obesity first caught the attention of the media, the national rate of obesity has doubled.¹ Now, more than one-third of all U.S. adults are obese. And despite hundreds of new (or cleverly recycled) “solutions” hitting the shelves in book or prepackaged food form each year, we just can’t seem to stem the tide. Our national weight problem is just the tip of the iceberg, however; being overweight is linked to some of the major causes of premature death, including heart disease, stroke, Type 2 diabetes, and some cancers.²

This book is primarily about low-carb diets—one of the more financially successful, and one of the most health-threatening, solutions proposed to meet our desire to shed pounds and become healthier. We’ll discuss why the low-carb diet is so appealing, how we’ve been tricked in thinking it’s healthy, and the truth about its health impacts. But this book is also concerned with the beliefs about nutrition that underlie those things: where the belief that carbs are bad came from, and why it has persisted despite so much evidence to the contrary.

There have almost always been fad diets with varying degrees of scientific merit, some more effective than others. Several decades ago, and still to a certain extent today, the most trusted advice was, essentially: eat less and exercise more. Weight loss was a matter of arithmetic—calories in vs. calories out. But we were also told that dietary fat is the problem. Fat is what makes us, well, fat. So if we want to lose weight, all we have to do is consume less of it.

But as the national obesity rate rose, it was clear that this advice on fat just wasn’t cutting it. The Standard American Diet (SAD) also wasn’t cutting it. We needed to rethink the way we looked at proper nutrition. It was during the 1980s, in the wake of these rising concerns, that the low-carb movement began to take hold. It hit its stride in 1988, with the publication of Dr. Robert Atkins’ New Diet Revolution, which was “new” only in that it followed Atkins’ 1972 book, Dr. Atkins’ Diet Revolution, which had not been especially successful in the marketplace. And this “new” book’s contents represented an appealing alternate belief system about weight, nutrition, and health.

In a nutshell, the low-carb movement told adherents to severely limit their intake of carbohydrates and instead to get the lion’s share of their calories from protein and fat. The problem with the SAD isn’t fat, the book claims, but carbs—those found in bread, rice, and pasta, in fruit and starchy vegetables. The best way to lose weight, Atkins proclaims, is to cut back on carbs.

And it worked! By feasting on bacon and steak and butter, low-carb dieters actually did drop pounds. Which would be great, except for one important thing: the low-carb diet is not good for human health. Report after report has shown the ill effects of a high-protein, high-fat diet. It’s just as bad, if not worse, than the SAD it seeks to replace.

In this book, I will explore a couple of important questions: Why do people think low-carb diets are a good idea? What’s the truth behind the low-carb hype? What’s the truly optimal diet for achieving an ideal weight while also obtaining health and longevity?

If there’s one thing I hope you’ll take away from this book, it’s this: the low-carb diet’s ability to bring about quick weight loss is far outweighed by the serious health problems that accompany such an animal foods–heavy diet.

THE LOW-CARB APPEAL

I’ve spent more than forty years in experimental nutritional research, first at Virginia Tech and then at Cornell, keeping up with the latest discoveries and doing my own work, both in the lab and in the field. And as a nutritional researcher, I was surprised at first by the popularity and commercial success of the low-carb diet, especially given its serious flaws. The research on high-protein, high-fat diets has consistently demonstrated that they have disastrous health effects and fail to secure compliance and long-term weight loss. So I think it’s useful to point out some factors that have contributed to these diets’ appeal.

It’s easy to imagine why dieters might be swayed—both then and now—by the idea of trying something radically different. Millions of Americans are on diets. Food manufacturers and marketers flood the marketplace with foods designed to help us lose weight and keep it off. Television features a steady stream of infomercials touting new gadgets, exercise routines, pills, and powders that can help us shed those unsightly pounds. And, apparently, none of it is working.

For a shocking visual, compare these two slides, taken from a CDC presentation. The first slide shows data from 1990 and is far from ideal:

Forty-six of the fifty-two states and other U.S. jurisdictions report adult obesity rates between 10 and 20 percent, with obesity defined as a Body Mass Index (BMI) greater than 30. No state has an obesity rate above 20 percent.

Now look at the data from 2010:

Just twenty years later, the thinnest states—with obesity rates under 25 percent—are all heavier than the heaviest states in 1990. And twelve states have cracked the 30-percent-plus mark.

The 2011 data, which haven’t made it into the slideshow yet, include a new category: 35 percent or greater adult obesity rate. While it wasn’t strictly necessary to add that category (Alabama came closest, with a 34.9 percent rate), the CDC were obviously planning ahead.³

Given the huge diet industry and its stunning lack of effectiveness, it’s only natural that alternative approaches would gain popularity. Low-carb was the alternative that gained the largest amount of public acceptance and hence the greatest market share. But why did low-carb beat out the other nontraditional approaches?

One of the main answers is marketing rhetoric. On this point, I have to take my hat off to Robert Atkins. One of the major themes of my new book on nutritional science, Whole: Rethinking the Science of Nutrition (2013), is that paradigms, or entrenched ways of seeing the world, are devilishly hard to change. But Atkins and his supporters turned a century of nutritional wisdom on its head, framing dietary fat and cholesterol as nutritional heroes and attacking anyone who pointed to research showing otherwise. They gave Americans permission to eat huge amounts of some of the unhealthiest foods on the planet, and to do so not only without guilt, but with feelings of pride and superiority. The most impressive legacy of the Atkins craze is a linguistic achievement: coining the phrase “low-carb” and thereby turning most plant foods—which were previously considered the healthiest dietary choices—into dangerous and fattening no-nos.

The appeal of this was immediate, for obvious reasons. After decades of believing that losing weight was possible only by subsisting on salads, depressing lunches of grapefruit halves and fat-free cottage cheese, and diet sodas that taste like battery acid, people were told to eat as much as they wanted of their favorite foods: steak, bacon, butter, lard, cream cheese, olive oil, mayonnaise, and eggs. Eating was fun again!

And lo and behold, people found that—in the initial stages of this diet—they did lose weight. It seemed like the very foods that doctors and public officials had been warning against all those years actually promoted weight loss more effectively than the tasteless zero-fat processed foods that took all the joy from eating.

Not only could the Atkins followers sate their fat- and protein-cravings without guilt, they could even feel superior to the poor fools who were still eating salads, going to weight-loss meetings, and counting calories.

The Atkins Diet didn’t just appeal to dieters; it was a boon to the meat, dairy, and egg industries as well. Not only could these companies now fend off public criticism of their products with low-carb “science,” but they also saw greater sales.

THE LOW-CARB LANDSCAPE

Not all low-carb diets are created equal, of course. The low-carb universe Atkins brought into being has grown to encompass many different diets and eating philosophies. But these are distinguished more by marketing than by substance—they all share the same fear and loathing of carbohydrates and recommend getting most of one’s calories from protein and fat.

Atkins

While Robert Atkins is the father of the modern low-carb movement, he didn’t come up with the low-carb concept, something he freely admits in his books. The first person on record as having used this type of diet was William Banting, a British undertaker, in the 1860s. Banting, at the age of sixty-six, tried a low-carb diet at the recommendation of his physician, Dr. William Harvey. He lost body weight in the first few weeks and commented that he might like to continue the diet—though the longer-term results of Banting’s alteration in diet, to my knowledge, were never clear. A few other medical practitioners experimented with low-carb diets with their patients over the next century, but the idea didn’t enter mass public consciousness until the 1972 publication of Dr. Atkins’ Diet Revolution.

Riding the wave of the low-carb diet’s near-term success, Atkins authored many additional books before his passing in 2003. His professional career morphed into an empire; as of this writing in 2013, the 1988 Dr. Atkins’ New Diet Revolution has sold more than 15 million copies, and Atkins Nutritionals, Inc., which produces and licenses Atkins-approved products, achieves annual sales in the millions of dollars. The Atkins Foundation funds research on the low-carb diet as it relates to obesity, Alzheimer’s, prostate cancer, and other diseases. And the Atkins empire perseveres, despite its founder’s death and a descent into bankruptcy following company mismanagement in 2004–2005; its present-day business still claims a big piece of the weight-loss market.

Low-Carb Spinoffs

Smelling profits, many other doctors and authors put their own spin on the low-carb phenomenon and created their own books, diets, and products. Most prominent among them are Mary Dan and Michael Eades’ Protein Power (1995), Barry Sears’ Enter the Zone (1995), Peter D’Adamo’s Eat Right 4 Your Type (1997), Loren Cordain’s The Paleo Diet (2002), Arthur Agatson’s South Beach Diet (2005), and Eric Westman’s The New Atkins for a New You (2010). Like younger siblings struggling to stand out, these various authors and their supporters go to great lengths to distinguish their “correct” diet from the others. The South Beach Diet prefers olive oil to butter and emphasizes leaner cuts of meat. Protein Power adds lots of water and nutritional supplementation to compensate for the low-carb diet’s inadequacies. Enter the Zone seemingly dismisses the low-carb idea by recommending “only” 30 percent protein but still relegates carbs to less than half your total calories. (That’s still low carb!) Even The Paleo Diet, despite its positive emphasis on whole foods, is just another version of the same low-carb, high-protein, high-fat idea (see Appendix). These spinoffs all occupy the same very thin slice of the human diet continuum.

In addition to their carbophobia, these authors have two other things in common: no experience in scientific research and a vast fortune generated by the sales of their shakes, powders, extracts, oils, bars, and even chocolates, along with a second fortune amassed through licensing their trademarked seal of approval.

The net effect of all this differentiation and marketing has been the normalization of low carb on a cultural level. Restaurants routinely offer low-carb menu options. It’s expected that someone watching their weight will bypass the dinner rolls. And whereas twenty years ago you would have raised an eyebrow (and a few concerns for your sanity) were you to sit down to a meal of bacon, butter, and beef for the purpose of shedding pounds, these days that’s a perfectly normal approach to weight loss. When absurdities get repeated often enough, they start sounding like truth.

THE REAL TRUTH ABOUT LOW-CARB DIETS

As I mentioned, low-carb diets are often pretty good at bringing about short-term weight loss. But that benefit comes with huge downsides. Low-carb diets target excess weight without paying attention to the underlying cause or causes of that weight, which leads to other symptoms. Low-carb diets often make those other symptoms, as well as the cause itself, worse.

What’s the difference between attending to a cause and treating a symptom?

A brown lawn, for example, is a symptom. It’s an unsightly, possibly embarrassing symptom that could get your neighbors shaking their heads and talking about you behind your back. “Look how he lets his lawn go,” they might mutter. “Why doesn’t he do something about it?”

So along comes the lawn-care specialist with a solution to your problem: green paint.

Voilà—problem solved!

Well, not exactly.

After painting the grass, your lawn will look green temporarily, but eventually the paint will wear or wash away, and then you have to call the lawn painter back in. The paint doesn’t do anything about the poor health of the grass that led to it turning brown in the first place. And if the paint is toxic, it can even make the health of the grass worse. If you really want a lush green lawn—a healthy lawn that is naturally green—you need to improve the soil: add nutrients, remove toxins, water appropriately, and use the right grass seed for your environment. In other words, focus on the root causes, not just the visible symptoms.

If you want to lose weight, focusing solely on weight loss—as the low-carb diet does—is as unproductive as painting your lawn green.

The low-carb diet’s first major flaw is that it’s short term. Over the long term, low-carb diets don’t fulfill their promise to dieters, which is that the diet will help them reduce their weight and sustain the change. Observation studies of populations overwhelmingly show that high-protein, high-fat diets, which reflect the long-term consumption of animal-based and highly processed food products, are associated with more health problems, many of which are associated with obesity.⁴

Americans are getting heavier and sicker, despite all the modern advances in medical care and technology. We’re making no significant inroads in reducing rates of cancer, heart disease, stroke, diabetes, and dozens of other diseases intimately connected with obesity. It’s just that, unlike diabetes or high blood pressure, obesity is a more visible symbol of the problem.

In truth, the obesity epidemic and the health crisis are two sides of the same coin. You can’t solve one without solving the other. That’s as true on an individual basis as it is for society as a whole. Obesity is a symptom, just like hypertension, clogged arteries, angina, chronic shortness of breath, belly pain, dizziness, constipation, and hundreds of others. Yet we largely, and wrongly, treat obesity as if it’s a separate thing—a separate disease.

While there’s a lot of overlap between a healthy body weight and overall health, they aren’t synonymous. You can lose a lot of weight by getting cancer, and you can keep it off by dying, but I don’t recommend that approach! Charitably, we could say that low-carb advocates are using weight loss as a Trojan Horse to get people to improve their diets and overall health—although there’s little evidence for this generous interpretation. As Atkins himself was both obese and quite ill from the known consequences of a high-protein, high-fat diet at the time of his death,⁵ it’s clear that this community isn’t taking seriously the damning data on long-term health outcomes.

Two original research papers reveal more about the consequences of the Atkins Diet than any others because they were published by supporters of the Atkins Diet and were funded by the Atkins organization. In one paper,⁶ users of the Atkins diet, when compared to control subjects of “low-fat” dieters (dieters who were getting “only” 30 percent of their calories from fat), suffered more constipation (68 vs. 35 percent), more headaches (60 vs. 40 percent), more halitosis (38 vs. 8 percent), more muscle cramps (35 vs. 7 percent), more diarrhea (23 vs. 7 percent), more general weakness (25 vs. 8 percent), and more rashes (13 vs. 0 percent)—even those Atkins diet users who were taking vitamin supplements. In the other paper,⁷ similar prevalences were seen for the Atkins dieters for constipation (63 percent), headaches (53 percent), and halitosis (51 percent).

These Atkins Diet side effects are consistent, and the research is quite convincing. That is, when compared with the already poor Standard American Diet (SAD), which is high in fat and protein, the Atkins Diet, even higher in fat and protein, leads to far more negative health outcomes, even in the short term.

So why do dieters still believe the low-carb hype? It has a lot to do with how convincing the low-carb movement’s arguments sound—even though those arguments are consistently contradicted by the science.

GARY TAUBES AND LOW-CARB SLEIGHT OF HAND

The best lies contain a kernel of truth, and that’s certainly the case with the work of journalist Gary Taubes, by far the most eloquent and influential present-day spokesperson for the low-carb movement. Taubes’ two bestselling books, Good Calories, Bad Calories (2007) and Why We Get Fat (2011), make the low-carb case in an entertaining and, to many, compelling fashion.

Taubes is not, of course, the only person who writes in support of the low-carb diet, but I’ve chosen to center my critique around Taubes’ writings because they represent the most comprehensive and evidence-rich expression of the low-carb idea. Taubes’ work also provides—inadvertently, no doubt—a survey of many of the errors, logical problems, and sleights of hand common to low-carb advocates. By pointing out Taubes’ errors and exposing his faulty reasoning, I hope to show the failures and intellectual poverty of the entire low-carb movement.

The first and perhaps most damning problem is the misreading of history and of the supposed link between low-fat diets and obesity. Taubes tackles this history in Good Calories, Bad Calories, a book billed as required reading for those interested in the evidence supporting a low-carb diet. While Taubes’ account is certainly comprehensive, his interpretation is, shall we say, creative.

WHERE TAUBES GETS IT RIGHT

Taubes begins with a kernel of truth, rightly pointing out that the effectiveness of counting calories is a myth. He also gets right some of the important history of the narrative on diet and health of the past five decades. And in his technical arguments on the underlying biochemistry of obesity, he gets some of these details right as well. But considered in isolation and spun into a narrative about the evils of carbs, these partial truths end up misleading rather than informing.

Taubes correctly points out that many early researchers, in the way they crafted their studies and reported their findings, were confusing the three main hypotheses for the causes of obesity and related illnesses: excess calories, excess fat, and excess carbs. According to the first hypothesis—by far the most common—we gain weight because we ingest more calories than we burn. This is the hypothesis I mentioned earlier, which you still hear being invoked today as if it’s the most obvious thing in the world: “eat less, exercise more.” Simple arithmetic. To his credit, Taubes does a masterful job of debunking this dangerous oversimplification.

Taubes goes on to argue, correctly, that creating long-term health by controlling calorie consumption does not work—a very important observation little understood by professionals and nonprofessionals alike. Most people cannot maintain significantly lower calorie consumption for long periods of time, even though they may be able to do so for a short while. That is, “diets” don’t work—not because our willpower isn’t up to it but because of our biological inability to healthfully maintain the substantially lower calorie consumption required to significantly decrease disease formation.⁸ In any case, Taubes says, generally it is not the amount of calories consumed that matters most but the way calories are metabolized and distributed throughout the body (something we’ll discuss in more depth in a few pages). In fact, Taubes argues that increased calorie consumption is the effect, not the cause of obesity—that we gain weight for other reasons and then require more calories to sustain that weight. Something else is causing obesity, and it is doing so by determining how our ingested calories are metabolized and used.

I applaud Taubes’ demolishing the calorie hypothesis. In fact, I have long said that we should be careful not to emphasize the “calories in; calories out” hypothesis or describe calories in precise quantities as if they are physical entities, like molecules, that have structure and form, because doing so only gives them added importance.

A calorie is only a measure of energy contained within a molecule, especially within the chemical bonds that bind atoms. Think of a pile of wood. We know that there is energy in that pile of wood, but we cannot see or feel it. When we put a match to the wood, however, we feel that energy escaping as the wood bursts into flames. The calorie contents of nutrients are also determined by measuring the heat nutrients release when burned. To calculate this, macronutrients (fat, protein, and carbohydrates, the nutrients that provide the vast majority of the weight of food) are burned in controlled conditions in a laboratory, and the heat emitted—the temperature change—is measured as calories. (I prefer to call this property “energy” but will stick with “calories” here because of the term’s broad familiarity.)

The amount of calories needed to produce a noticeable change in body weight, up or down, is very small—a notion that also sidetracks our emphasis on calories. A difference of fifty calories can be difficult to distinguish in the context of a day’s total food intake; it’s equivalent to an average of less than a teaspoon of oil per day. Yet a difference of fifty calories retained by the body per day can theoretically cause a gain or loss of five to ten pounds of body weight per year.⁹ The problem is that consumption of calories does not equal retention of calories; retention of calories is not something we can consciously control by counting. So, in this respect, Taubes is correct: calorie intake or expenditure, except in the extreme, does not matter as our findings in China confirm.¹⁰

WHERE TAUBES GETS IT WRONG

Taubes parts company with the evidence when he gets into the identification of where “bad calories” come from. Taubes sees excess consumption of calorie-contributing carbohydrates (the second of the three competing theories mentioned previously) as the root of all dietary evil. In his view, the consumption of sugar (table sugar or sucrose) and other carbohydrates (i.e., refined carbohydrates, such as starch and fructose) is responsible for the obesity epidemic in the United States and much of the rest of the world. And he blames this spike in carbohydrate consumption on the government’s promotion of the third competing theory: that calories from fat make us fat. In Taubes’ view, the fear of fat engendered by government low-fat policies drove the American public straight into the arms of a high-carb diet because it encouraged the replacement of this fat with carbohydrates. In short, Taubes says that too many carbs is the problem, while the government (or his interpretation of it) says the problem is too much fat.

Taubes argues on historical and scientific grounds that excess fat consumption cannot account for the alarming rise in obesity during the past thirty years the way government pronouncements suggest. Most readers will be familiar with the widespread recommendation to use low-fat foods, as well as the multitudes of “low-fat” food products on the market. Taubes presents a seemingly plausible account of how scientists working in this field got it wrong, partly because they were not very imaginative and partly because they became entrenched in a worldview that discouraged professional challenge against the much-publicized low-fat-focused hypothesis lest they be ridiculed or even risk losing their professional standing. Fat, not carbohydrates, Taubes says, should be our primary source of energy. Fat is good, he says, and not something merely dumped into a body reservoir that eventually becomes adipose tissue.

Before going further, let’s consider what a carbohydrate actually is, especially because Taubes rather arrogantly lambasts scientists for not knowing the properties of this nutrient. (In my experience, it’s really journalists like Taubes, corporate marketing agents, and even some clinicians who are confused about carbohydrates’ definition and meaning.)

The Diversity of Carbohydrates

Carbohydrate is a nutrient found almost exclusively in plants. It is a collection of simple to very complex chemical molecules. Simple carbohydrates include monosaccharides (like glucose, fructose, galactose, mannose, etc.) and disaccharides, which are made up of two chemically bonded monosaccharides (like sucrose [table sugar, made from glucose and fructose] and lactose [milk sugar, made from glucose and galactose]). Linked chains, or polymers, of three or more monosaccharides are called polysaccharides. Glucose (the same molecule as in blood sugar) is the most common monosaccharide unit in polysaccharide chains, with fructose being nearly as common in some foods. Starch, which is the primary polysaccharide in foods like potatoes and cereal grains, is a network of long chains of glucose molecules.

Monosaccharides and disaccharides are often considered “simple” carbohydrates because their molecular size is small, they readily dissolve in water, and they are easily digested and absorbed into the bloodstream. Some people infer that starches are also “simple” because they, too, dissolve in water (though they turn it into a gel or paste) and are readily broken down during digestion into glucose, which is then absorbed into the bloodstream.

Other carbohydrate types are much more complex. Elaborate networks of polymers are formed from chains of monosaccharides, sometimes also including amino acid and fat-like molecular side chains. These polymer networks exhibit a wide variety of chemical, physical, and nutritional properties. A large group of substances generally referred to as the dietary fiber group, for example, are, unlike their simple carbohydrate cousins, generally not digested and absorbed in the gut. Nonetheless, these complex, fiber-like substances still participate in vitally important biological activities: they interact with intestinal microorganisms that break them down into products that benefit the rest of the body, especially the intestines. Indeed, simple and complex carbohydrates, when working together, provide diverse health benefits, including the provision of energy.

Whenever we encounter diversity in nature, we should be slow to dismiss it as unnecessary or unfortunate. A broad spectrum of carbohydrate digestibility and function is very important: it allows the body to adapt to different conditions, ranging from the need for a quick burst of energy to the facilitation of digestion and absorption of other nutrients in the gut.

It’s true that sucrose, the simple disaccharide that comprises table sugar, can be harmful when consumed in isolation. Sucrose is known to have little or no useful health value when extracted from sugar cane and sugar beet plants and added in isolated form to other foods. High-fructose corn syrup is another simple monosaccharide of more recent commercial vintage and exploitation. The latest studies suggest that its effects are as bad as those of sucrose,¹¹ if not worse.¹²

In order to use this evidence in support of the low-carb movement, Taubes performs a bit of sleight of hand, the crux of which is: refined sugar is bad, therefore all foods that contain sugars (i.e., carbs) are bad. This is poor logic even in the classical sense. We can also highlight the flaws in this reasoning by considering another carbohydrate found in plant food—fiber—and comparing its health effects when in its natural state and when processed, isolated, and consumed as a substance separate from that natural state.

Dietary fiber is extracted from all kinds of whole plants in order to add it to muffins and other baked goods as “bran.” Marketers then claim health benefits from these baked goods, citing the research evidence on the goodness of fiber. But bran doesn’t help us when it’s been extracted from whole plants and then stuck into processed and fragmented foods like breads and breakfast cereals. Although there is some evidence that bran supplements may reduce certain indicators of serious health problems, I find no evidence that, over the long term, this is a good option for actually preventing or treating these problems.¹³

Whole foods that contain dietary fiber, in its many complex forms, are associated with lower incidence of colon cancer, lower blood cholesterol, and lower breast cancer–inducing estrogen levels. The use of bran isolated from these foods is more about marketing than health. This holds true for many isolated nutrients, which either have no positive health benefits or actually result in damaging effects.

If Taubes and his low-carb compatriots are against ingesting refined (i.e., extracted) sugars, they should say so, and I’d be among the first to support their crusade to eliminate those sugars from our diets. But instead, they tar the entire class of carbohydrates with the same brush, which is an intellectually superficial and dishonest move. (Taubes is more careful than some other low-carb cheerleaders, but not completely so. He should be proactively emphasizing this discrepancy, not allowing it to smolder just below the public narrative.)

Because fruits, vegetables, and whole grains are all high in carbohydrates, lumping all carbs together as unhealthy means demonizing plant-based foods as well as simple sugars. A diet low in carbohydrates is unavoidably a diet high in fat, especially saturated fat, because eliminating carbohydrates means relying on large quantities of animal-based products for energy and other nutritional benefits. Virtually by definition, therefore, a low-carb diet emphasizes the consumption of animal-based foods, while a low-fat diet emphasizes the consumption of plant-based foods. In my experience, it is this emphasis given to animal-based foods in low-carb (and thus high-protein, high-fat) diets that is the chief motivation of low-carb advocates.

The dramatic shift in consumption suggested by Taubes’ oversimplification of the definition and meaning of carbohydrates has momentous consequences. Not only does shifting to a diet low in carbs severely minimize our intake of antioxidants, complex carbohydrates, vitamins, and certain minerals, it also shifts our dietary source of energy from carbohydrates to fat and encourages consumption of protein far above the required amount.

Why is this such a terrible thing? Because the foods we choose to meet our energy needs make a big difference in whether we experience good or ill health.

Number of Calories Versus Source of Calories

If by “good and bad calories,” Taubes means “good and bad sources of energy”—in effect, good and bad foods—he and I agree, at least in principle. Plant- and animal-based foods are hugely different in terms of their nutrient contents, and watching what foods you consume is far more important than obsessing over calorie-counting without respect to where those calories come from.

Take, for example, our research into the effect of dietary protein on cancer growth in experimental animals, involving about twenty-five individual experiments conducted over about thirty years. The animals consuming the lowest amount of protein (5 percent of total calories) had far less cancer than their higher-protein-consuming counterparts, while consuming an average of 2 to 3 percent more total calories (or, as I prefer to say, more total energy). This is an important observation: more calories consumed, but less cancer.

It was not easy to convince some of my colleagues of this finding because of their long-standing and almost certain belief that our conclusion should have been exactly the opposite: that increased calories lead to increased rates of cancer (as well as other disease). These beliefs on the calorie-cancer connection were based on prior experimental studies, which showed reduced cancer occurrence when calorie consumption was reduced by a hefty 20 to 30 percent or more.¹⁴