science gone wrong, pt 3: is eating fat actually good for you?

So this was initially going to be a follow-up to the post where I talked about chest pains and the fear that comes with them. Then I started law school, and our little blog has essentially lain dormant ever since.

But way back when (back when I was amibitious about my blogging), I was going to tell you that as a result of that scare (and being told by a crank of a cardiologist that I needed to lose weight), I read Gary Taubes’ Good Calories, Bad Calories. It’s an exhaustively researched and persuasively argued brick of a book; Taubes traces the history of modern ideas about diet and concludes that the dietary recommendations we all grew up with — avoid fat and animal products, eat mostly grains — were born more out of argument from authority than out of sound biochemical research.

The belief that there’s something suspicious about fat (especially animal fat) is so pervasive that even food writer Michael Pollan, who wrote of Taubes’ book that it is “vitally important” and “destined to change the way we think about food,” nonetheless still recommends that people eat “mostly plants.”

And this makes sense, right? Isn’t fat the big killer? It’s so obvious: eating cholesterol-rich foods leads to high blood cholesterol, which leads to atheromas building up in our blood vessels and killing us. And being fat is obviously the result of eating too many calories, and fat has more than twice as many calories as carbohydrates like starch. So if there are two absolutely iron-clad, bona fide rules about the relationship between diet and health, it’s that we should eat less animal fat and fewer overall calories.

But what if neither of those strategies is backed up by good science? What if reducing dietary fat (and replacing it with carbohydrates) is actually incredibly harmful and leads to poorer health outcomes, while consciously attempting to restrict calories is persistently ineffective as a weight loss tool?

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Taubes, a science journalist and fellow at the UC Berkeley School of Public Health, is consciously and deliberately swimming against the tide of dominant nutritional opinion — apparently because he thinks it’s based on bad science. His main claims are twofold: first, fats (even saturated fats) are not as bad for you as we’ve been told; and second, carbohydrates (especially simple sugars), are much, much worse for you than we’ve been led to believe.

Taubes made the first point in a 2002 New York Times Magazine article, “What If It’s All Been A Big Fat Lie?”, where he noted that the “animal fats = high cholesterol = arteriosclerosis = heart disease” message is complicated, and possibly undermined, by the actual science on how diet translates into lipoproteins:

Few experts now deny that the low-fat message is radically oversimplified. If nothing else, it effectively ignores the fact that unsaturated fats, like olive oil, are relatively good for you: they tend to elevate your good cholesterol, high-density lipoprotein (H.D.L.), and lower your bad cholesterol, low-density lipoprotein (L.D.L.), at least in comparison to the effect of carbohydrates. While higher L.D.L. raises your heart-disease risk, higher H.D.L. reduces it.

What this means is that even saturated fats — a k a, the bad fats — are not nearly as deleterious as you would think. True, they will elevate your bad cholesterol, but they will also elevate your good cholesterol. In other words, it’s a virtual wash. As Willett explained to me, you will gain little to no health benefit by giving up milk, butter and cheese and eating bagels instead.

But it gets even weirder than that. Foods considered more or less deadly under the low-fat dogma turn out to be comparatively benign if you actually look at their fat content. More than two-thirds of the fat in a porterhouse steak, for instance, will definitively improve your cholesterol profile (at least in comparison with the baked potato next to it); it’s true that the remainder will raise your L.D.L., the bad stuff, but it will also boost your H.D.L. The same is true for lard. If you work out the numbers, you come to the surreal conclusion that you can eat lard straight from the can and conceivably reduce your risk of heart disease.

Taubes explored the second proposition — that sugars and starches are actually hazardous — in a 2011 article, also for the Times, “Is Sugar Toxic?”:

You secrete insulin in response to the foods you eat — particularly the carbohydrates — to keep blood sugar in control after a meal. When your cells are resistant to insulin, your body (your pancreas, to be precise) responds to rising blood sugar by pumping out more and more insulin….

[H]aving chronically elevated insulin levels has harmful effects of its own — heart disease, for one. A result is higher triglyceride levels and blood pressure, lower levels of HDL cholesterol (the “good cholesterol”), further worsening the insulin resistance — this is metabolic syndrome….

[W]hat sets off metabolic syndrome to begin with[…?] What causes the initial insulin resistance? There are several hypotheses, but researchers who study the mechanisms of insulin resistance now think that a likely cause is the accumulation of fat in the liver….

As it happens, metabolic syndrome and insulin resistance are the reasons that many of the researchers today studying fructose became interested in the subject to begin with. If you want to cause insulin resistance in laboratory rats, says Gerald Reaven, the Stanford University diabetologist who did much of the pioneering work on the subject, feeding them diets that are mostly fructose is an easy way to do it. It’s a “very obvious, very dramatic” effect, Reaven says.

By the early 2000s, researchers studying fructose metabolism had established certain findings unambiguously and had well-established biochemical explanations for what was happening. Feed animals enough pure fructose or enough sugar, and their livers convert the fructose into fat — the saturated fatty acid, palmitate, to be precise, that supposedly gives us heart disease when we eat it, by raising LDL cholesterol. The fat accumulates in the liver, and insulin resistance and metabolic syndrome follow.

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Is Taubes right, here? Are these actual facts? Because if they are — and if the rest of Taubes’s exhaustive discussion of the research in the book is correct about the endocrinology of metabolic syndrome — then the information we’re given all day, every day about what’s good to eat and what we should avoid is precisely backwards, and we should all be eating a lot more butter.

It turns out, much to my surprise, that I am not a medical researcher. I can read individual studies well enough, but to really bear down on this issue would take… well, it would take a decade of being paid as a science journalist to do it, wouldn’t it?

So I’m in a weird position: Here’s a major challenge to the received wisdom about something as basic and well-known as nutrition. It’s by a highly respected science journalist — not a scientist himself, but a meticulous researcher who supports his arguments with copious and thorough citations. Is that a good enough source? Good enough to convince me to change my behavior?

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In April of last year, Taubes put his money where his mouth was, publishing the results of a blood lipids test in order to respond to Dr. Mehmet Oz, who had criticized Taubes’ high-fat, low-carb diet. (Taubes: “I do indeed eat three eggs with cheese, bacon and sausage for breakfast every morning, typically a couple of cheeseburgers (no bun) or a roast chicken for lunch, and more often than not, a ribeye or New York steak (grass fed) for dinner, usually in the neighborhood of a pound of meat.”)

That diet has also been my diet, and Elana’s diet, for about eight months. About three months after we started this project, I had bloodwork done for a physical myself, and I am pleased to report that both Gary Taubes and I have excellent levels of the various markers used to determine cardiovascular risk — high HDLs, low LDLs and triglycerides, low “C-reactive protein,” which measures vascular inflammation. Gary Taubes, Elana, and I have been eating a ton of animal fat and green veggies and almost no sugar, flour, or potatoes. (Taubes, I think, doesn’t eat any starchy vegetables or legumes; we are not so committed and occasionally eat beans.) We’ve lost weight (in my case, about 22 lbs, , felt less logey after meals, and still have really good blood cholesterol profiles and outlooks for cardiovascular disease.

Some caveats:

I haven’t been doing this very long. Perhaps all that bacon will catch up with me in a few years and ruin my blood lipid profile. But Taubes has been eating this diet for years. Of course….

This is a very small number of data points. That’s always the problem with experimenting on yourself, along with….

Confounding factors: Exercise is probably the big one. Immediately prior to starting this diet, I had been running only once or twice a week; around the same time I started eating low-carb, I started running two or three times a week. And then I switched, a few months after starting this diet, from running and hiking for exercise to cycling to and from school three to four days a week. This makes it look like maybe it was the exercise, not the diet, that brought off the pounds.

But take another step back on the timeline. I actually put on most of the pounds that I recently shed during my time in Iraq, when I was working out four to five times a week, and in the immediate aftermath of my Army career, when I was running two or three times a week and cycling everywhere I went. (I lived six blocks from Venice Beach.)

It’s true I put on the last seven or eight pounds during a period of low activity. But I’m guessing Taubes would say that we’re looking at the arrow of causality wrong — he would say that when you’re not eating sugar and starches, your body actually regulates energy in a way that makes you more able and willing to engage in strenuous exercise. Less insulin resistance means less insulin in your bloodstream, and it’s insulin that essentially channels calories into your fat cells and away from where they’re needed in other tissues, causing you to be hungry and have less energy. In other words, according to Taubes, lean athletes aren’t lean because they’re athletes; they’re athletes and they’re lean for the same reason — because their bodies are regulating energy usage properly.

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Not everyone is convinced. Perhaps most notably, well-known science-fad skeptic Michael Fumento published a lengthy and somewhat cranky takedown of “What If It’s All Been A Big Fat Lie?” in Reason magazine, complaining that Taubes (a) ignored a number of studies that contradicted his conclusions and (b) selectively quoted a number of researchers who were displeased with the way their research was portrayed in the article. Taubes responds here, quoting his sources at length; I’ll leave it to you to read, but the exchange is a great display of science-journo pugilism.

Fumento, though, didn’t have the benefit we now have of an additional decade of research (and an additional decade of Americans eating more and more sugar and getting fatter and sicker than ever before). Here are two reasonably competent, well-reasoned sources to consider: first, not long after the Fumento-Taubes exchange, Stanford researchers led by Christopher Gardner conducted a two-year study called the “A TO Z Diet Study” — “A TO Z” because they compared outcomes from four popular diets: Atkins (an ultra-low-carb, high-fat diet), Traditional (restricted calories), Ornish (super-low-fat), and the “Zone” (moderately low-carb). From the abstract:

Weight loss at 12 months was the primary outcome. Secondary outcomes included lipid profile (low-density lipoprotein, high-density lipoprotein, and non–high-density lipoprotein cholesterol, and triglyceride levels), percentage of body fat, waist-hip ratio, fasting insulin and glucose levels, and blood pressure….

Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months…. At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups.

Here’s the weight loss in graph form, for those who like numbers:

Weight loss from baseline.

But to me, by far the more interesting data is about the “secondary” outcomes — i.e., the predictors for metabolic disorder and cardiovascular disease. After all, as I noted in the previous “science gone wrong” post, being fat is not, in and of itself, unhealthy. It’s the weight gain associated with metabolic syndrome that’s a marker for many of the most serious diseases. So here is a table comparing these outcomes across the four diets (for best results, ctrl-click the image to open in a new tab or window, then click on the new image to enlarge):

The key indicators are pretty stunning — HDLs go up much more on Atkins than on any other diets, while triglyceride levels positively fall through the floor. Blood pressure is also lowered more by Atkins than by any of the other diets. (The Ornish diet, which is a draconian low-fat regime, is perhaps the most instructive comparison.) The conclusion is hard to avoid — eating mostly animal fat is no worse for you, and possibly much better for you, than eating a low-fat, plant-carbohydrate-based diet.

(You can see Gardner, himself a vegetarian, lamenting this conclusion in a presentation of the study’s results here.)

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As for the second piece of the Taubes thesis — the idea that it’s carbs that are killing us — here’s a compelling, if occasionally dorky, talk by endocrinologist Robert Lustig on the way sugar has pervaded everything we eat and the damage it’s doing to our bodies. The endocrinological arguments — starting at around the 42:00 mark, if you don’t have time to watch the whole thing — are almost identical to those put forward in Good Calories, Bad Calories.

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I’ve come away convinced. I eat as much as I want, whenever I want, and I’m 22 lbs lighter than I used to be. One of the scientists interviewed by Michael Fumento dismisses this kind of weight loss as mere calorie restriction through boredom, asking, “If you’re only allowed to shop in two aisles of the grocery store, does it matter which two they are?” Taubes would say, and I would agree, that it matters a lot. The whole point of an endocrinological approach, as Lustig makes clear in the lecture above, is that sugar tends to trick your body into thinking it’s still hungry even after it’s had enough calories. (According to Lustig, fructose is the real villain in this regard, because it’s metabolized solely in the liver and doesn’t suppress the hunger hormone ghrelin or stimulate the satiety hormone leptin.)

If you eat from the “aisles of the grocery store” containing sugary snacks, in other words, your body will not get adequate signals that it’s had enough calories, and you’ll continue to eat. The whole idea of being “bored” with the limited food choices presented by an Atkins-type diet presumes that you’re eating for entertainment, rather than because you’re hungry. The whole thrust of the endocrinological approach, on the other hand, is that people who eat a lot of sugar still feel hungry, and that’s why they eat.

There’s also the added benefit — and this is what has me and Elana really convinced — that when you aren’t eating carbs, you don’t get “food coma” (aka an insulin spike after eating). You also don’t get really, really hungry, because, since the level of insulin in the bloodstream is consistently lower, your fat cells are more readily able to mobilize energy when you haven’t eaten in a while. (Insulin inhibits the ability of the fat cells to release calories.) So rather than hunger pangs and yo-yoing energy levels, you have a fairly consistent level of energy throughout the day.

And then there’s the whole not-dying-of-metabolic-syndrome angle. That seems good, too.

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Are there downsides? Sure.

I like cake. Also Mike&Ikes, Junior Mints, doughnuts….

It works differently on different people. Just be aware. If, like me, you’re prone to putting on fat around the middle (i.e., the kind of fat that presages metabolic syndrome and heart disease), you’re probably going to lose a lot of that fat, and that’s a good thing. But if you’re generally plump, the weight loss may be slower, and you may never be ultra-lean. (On the other hand, you probably aren’t as likely to suffer the same bad health outcomes — so don’t worry about it.)

You have to cook a lot. A lot. This is really key to the whole program, in fact. It’s basically a diet of whole foods. Whole cuts of fatty meat and a lot of vegetables, augmented with a decent amount of dairy. None of this is food you can just throw together lazily at the last minute. (Our go-to “quick” meal is Italian sausages and two or three green veggies.)

It’s really, really hard to eat at someone else’s house. If you’re going home for Christmas, you really have to come to grips with the fact that you’re either going to (a) take a holiday from your diet for a few days or (b) be a really awful houseguest. (There’s no polite way to commandeer someone’s kitchen to make bacon and eggs every morning when what they’re offering is toast and jam.)

The entire commercial food supply chain is out to fuck with you. Seriously, you must eat whole foods. Anything even remotely pre-packaged or processed for your convenience is going to add the sugar back in. (Beware restaurant food.) And most of the supply chain is now dedicated to the low-fat ideology, and so perfectly good fat is frequently stripped out of things that would be both healthier and better-tasting if the fat were left in. (Did you know, for example, that plain yogurt is not revolting? I didn’t either, until I tried Trader Joe’s French Cream Line whole-fat yogurt….)

The whole thing is expensive as fuck. Whole cuts of meat are expensive. Fresh vegetables are highly perishable. We are constantly grocery shopping and you don’t want to know what we spend on food in a month. Seriously — this diet is a diet of privilege.

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That last point is a disturbing one. Almost all of our gains in food productivity in the past two centuries have derived either from increased efficiency at growing and exploiting grains (i.e., carbs), or from more and more ruthless exploitation of animals. Way up above I quoted Taubes as saying he usually eats a grass-fed steak for dinner. Well, of course he does. He writes for the New York Times. He’s written two best-selling books. I’ll bet any cow Gary Taubes eats was massaged and played classical music every night before lying down on its bed of silk brocade.

But there are just not enough locally-sourced, grass-fed, cruelty-free cows in the world to feed everyone alive at the moment — let alone everyone who’ll be born in the coming decades. One of Michael Pollan’s other well-known mantras is “Eat food.” By which he means, eat whole foods — things your great-grandmother would have recognized as food. Not Hot Pockets and Top Ramen and Twinkies. But people aren’t shunning delicious roasts and green vegetables because they’re self-destructive assholes; most people eat extruded soy/corn product because it’s cheap and because it’s convenient enough to eat that they can keep working. In the end, the diet that might be best for us is one most people will never be able to afford. That’s a pretty grim thing.