I’m a fan of the EconTalk podcast and have been listening religiously for the better part of a year. The host, Russ Roberts, brings a variety of guests onto the show and ties diverse topics back to the fundamentals of economics. One of my favorite guests has been Gary Taubes, whom Russ brought on for the first time in November of last year to discuss fat, sugar and scientific discovery. The contrarian nature of his opinions interested me immediately, but it wasn’t until Taubes was on Econ Talk a second time that I felt compelled to pick up a copy of his book Good Calories, Bad Calories.
Published in 2007, Good Calories, Bad Calories is an extremely multifaceted book. Not only is it a comprehensive history of epidemiological studies on nutrition and obesity treatments, it’s also a exposé on junk science and the dangers of politicizing public health. There’s a lot more going on in this book than I’ll be able to give justice to here, but Taubes’ main thesis is that obesity, along with a whole host of other diseases, is caused by carbohydrate consumption; and, by extension, that low-carb diets are the only healthy way to achieve sustained weight loss.
That’s not a difficult concept to grasp. Most people already understand that to some extent. The problem is that people also have the contradictory belief that dietary fats are bad in that they too cause obesity as well as heart disease. I didn’t fully grasp how diametrically opposed these two ideas are until reading this book.
Taubes devotes the first portion of the book to the fat-cholesterol hypothesis — that diets high in fat and cholesterol cause heart disease. He attacks this myth systematically, calling it into question with the very data used to corroborate it. Taubes argues that researchers who believed this hypothesis never truly attempted to disprove it as the scientific method calls for. Rather, they promoted it through systemic group think, confirmation bias, and by politicizing the issue. They claimed, and still do, that “the verdict is in” (whenever I hear that phrase the “junk-science alarm” in my head implodes).
The dangers of this hypothesis, other than the fact that it’s simply not true, are that if you cut fats out of your diet you are forced to replace them with carbohydrates. You can’t have a low-fat diet that’s also low in carbohydrates. It just doesn’t work that way. It’s about the same time this hypothesis was taught to the American public that obesity rates started to rise along with diabetes and heart disease. It’s a vicious cycle, where people know sugar and flower are bad for them but health officials have scared them into believing fats are even worse. The next logical step is for public health officials (generally not actual scientists) to recommend low-calorie diets that are ineffective and unsustainable, leaving the public confused and demoralized when it comes to maintaining healthy weight.
From there he delves into the carbohydrate hypothesis, which has been largely overlooked by western health officials since WWII. The essence of this theory is very easy to grasp; anything that spikes insulin levels causes weight gain. This is because insulin is the hormone the body uses to trigger fat storage. As the body is bombarded with carbohydrates, insulin spiking foods, it begins to become resistant to the hormone. The body then reacts by producing more insulin which, in turn, causes increased resistance. This cycle eventually leads to obesity, diabetes, and a host other health issues. Weight gain is an effect, not the cause of these health problems. For this reason, low-carb diets, which are actually what humans have evolved to eat, are the only way to stave off these so called “western diseases.”
I’ve drastically oversimplified, but Taubes wades deep into the science and gives both historical and political context, as well as some great anecdotes — my favorite example was the study that proved the dangers of all-meat diets by force-feeding rabbits (herbivores) meat. Along the way he debunks a number of myths that have baffled me for years:
- Fat stores = Caloric Intake – Energy Expenditure
- Sure, the First Law of Thermodynamics might apply to simple machines, but humans are anything but. Once hormones (estrogen, testosterone, growth hormone, insulting, etc) enter the equation, overall calorie intake has little importance compared to the type of calorie it is.
- Humans need to consume a wide variety of foods in order to get the needed vitamins and nutrients.
- I remember asking my high-school Human Physiology teacher something along the lines of, “Why are humans the only mammals that need such a wide variety of foods?” He didn’t have a good answer and neither does science; because we don’t. Hopefully we’ve all realized how asinine the Food Pyramid is by now, but if not, it’s time to move on.
- Eating just a few less, or burning a few more calories a day will lead to long-term weight loss.
- It’d be nice if cutting out the cream-cheese on your breakfast bagel or always taking the stairs would help you shave off a few pounds over a year, but it won’t. As mentioned above, the human body is a wonderfully complex machine. It’s capable of adjusting to fluctuations in its environment. Add a few hundred extra calories and the body will react systematically to simply burn them off without notice. Subtract a few, and the body will simple adjust the amount of energy available for physical activity. This equilibrium won’t be affected by exercise either. In Taubes’ own words, “Expending more energy than we consume does not lead to long-term weight loss; it leads to hunger.”
One of the aspects I enjoyed most about Good Calories, Bad Calories is that Taubes isn’t trying to convert the reader to his own specially formulated weight loss regimen with included point systems and snack bars. While he definitely has a strong opinion to get across, his aim is to convince the reader that current views on obesity, weight loss, and diabetes are not based on proper scientific research.
The scientific obligation… is to establish the cause of obesity, diabetes, and the chronic diseases of civilization beyond reasonable doubt. By doing so, we can take the necessary steps to prevent these disorders, rather than trying to cure them or ameliorate them after the fact. If there are competing hypotheses, it does us little good to test one alone. It does little good to continue basing public-health recommendations and dietary advice on association studies… that are incapable of reliably establishing cause and effect. What’s needed now are randomized trials that test the carbohydrate hypothesis as well as the conventional wisdom. Such trials would be expensive. Like the Diabetes Prevention Program and Look AHEAD, they’ll cost tens or hundreds of millions of dollars. And even if such trials are funded, it might be another decade or two before we have reliable answers. But it’s hard to imagine that this controversy will go away if we don’t do them, that we won’t be arguing about the detrimental role of fats and carbohydrates in the diet twenty years from now. The public will certainly not be served by attempts of interest groups and industry to make this controversy go away. If the tide of obesity and diabetes continues to rise around the world, it’s hard to imagine that the cost of such trials, even a dozen or a hundred of them, won’t ultimately be trivial compared with the societal cost.
While I feel that anybody would benefit from reading Good Calories, Bad Calories, it may be a daunting task for some. It’s an in-depth look at the science and history of public health as it pertains to obesity and diabetes. This is not a “diet book.” You won’t find a list of foods you should or shouldn’t eat within its pages (though you can easily reason that out afterwards). Nor will you find helpful weight loss tricks.
What you will find is that the evidence in favor of our society’s current view on diet and exercise is extremely lacking and that the evidence against it is quite strong. This book has convinced me to change my lifestyle. Although I don’t expect everyone to have the same reaction, Taubes gives ample validation to make anyone skeptical of public health guidelines. I strongly recommend Good Calories, Bad Calories, but even if you don’t pick up a copy I’d urge you to study these things out for yourself. Also, the next time you hear some advice from a public health institution, you’d be wise to take it with a
grain of salt gram of fat.