Critiquing Gary Taubes, Part 2: Atkins Redux

His position seems plenty clear to me as far as anyone's position is clear: Obesity isn't about pigging out, it's about consuming refined carbohydrates.

Yeah, I was trying not to pull you ahead. But dealing with the big picture is more my style.

Taubes certainly does say things that seem to suggest that, but what it would even mean for that to be true?

I think he says it pretty directly actually. Good Calories, Bad Calories:

When Rony discussed positive energy balance, he compared the situation with what happens in growing children. “The caloric balance is known to be positive in growing children,” he observed. But children do not grow because they eat voraciously; rather, they eat voraciously because they are growing. They require the excess calories to satisfy the requirements of growth; the result is positive energy balance. The growth is induced by hormones and, in particular, by growth hormone. This is the same path of cause and effect that would be taken by anyone who is driven to put on fat by a metabolic or hormonal disorder. The disorder will cause the excess growth—horizontal, in effect, rather than vertical. For every calorie stored as fat or lean tissue, the body will require that an extra calorie either be consumed or conserved. As a result, anyone driven to put on fat by such a metabolic or hormonal defect would be driven to excessive eating, physical inactivity, or some combination. Hunger and indolence would be side effects of such a hormonal defect, merely facilitating the drive to fatten. They would not be the fundamental cause. “Positive caloric balance may be regarded as the cause of fatness,” Rony explained, “when fatness is artificially produced in a normal person or animal by forced excessive feeding or forced rest, or both. But obesity ordinarily develops spontaneously; some intrinsic abnormality seems to induce the body to establish positive caloric balance leading to fat accumulation. Positive caloric balance would be, then, a result rather than a cause of the condition.”

Why We Get Fat includes more like the above, but the copy I have with me doesn't allow for easy copy and pasting. But that's the story basically. Yes, people who are fat are going to necessarily have had a positive caloric-intake balance from when they were not fat. But that doesn't mean that the causal node to intervene on is a) how much a person eats or b)how much they exercise. Taubes's claim is that the fat composition of your body is determined by your hormones, insulin in particular which is secreted based on your blood-sugar levels. Your body then overeats -- or avoids burning calories-- to compensate.

Illustrative of this effect are a wide variety of lab animal experiments that induce obesity by manipulating the animal's endocrine system while controlling food intake.

Why don't we start there. What do you find incoherent about that?

This idea of calorie intake and expenditure being an epiphenomenon... Taubes certainly does say things that seem to suggest that, but what it would even mean for that to be true?

"Epiphenomenon" is somewhat hyperbolic, but it does make a sensible claim. To make clear what that claim is, it is necessary to think about causal graphs, because intervention in a system to produce a desired result can only be successful if it is based on a correct understanding of how the system works.

"dW/dt = Calories in - calories out", while literally true, carries with it the suggestion that a sufficiently accurate causal graph for this problem is one with two arrows, from input to weight and from output to weight. All you have to do to lose weight is to eat less and/or exercise more.

If the causal model is correct, the predicted result of an intervention will happen. If the predicted result does not happen, the model is wrong.

It seems to be more often the experience than not, that the predicted result does not happen. This brings the model into question.

Causal models make two sorts of claim: the claims that are seen, and the claims that are not seen. The claims that are seen are the variables and the arrows of the model: they claim that these properties of the world exist, and these causal influences exist among them. The claims that are not seen are the absences of variables and arrows. Where there is no arrow, the model claims that there is no direct causal effect. Where there is no variable, the model claims there is no other phenomenon in the world causally relevant to the things being modelled.

To repeat in the face of the failed prediction, "but...input minus output!" is to attend only to the claim that is seen. One of the claims that is not seen in this model is the absence of an arrow from input to output. Suppose we hypothetically add one: suppose that restricting calorie intake makes the body reduce its expenditure also. (Or in concrete terms: skip eating for a day and collapse with exhaustion.) What is now the effect on weight of eating less? That depends on the details and relative magnitudes of how these things influence each other. That is just one example. There are many ways in which "dW/dt = Calories in - calories out" could be embedded in a larger graph for which the claimed remedy for overweight will fail. When they fail, it is not because "dW/dt = Calories in - calories out" is false, but because it is incomplete.

For the case of growing children, where it is was said that they eat because they are growing, rather than growing because they eat, the claimed causal graph appears to be something like this: the body's internal processes of development cause a demand for food; the demand for food causes eating; eating makes materials available for growth; growth is sensed by the body's internal processes of development, which adjusts demand for food accordingly. The causal arrows form a cycle, part of which I've nebulously called "the body's internal processes". There will be an arrow into that node from other internal processes, specifying how fast to grow. (Observe that overfed chidren do not develop normally, but faster; they develop at the same speed and also grow fat.) That is what is driving the cycle, hence the paradoxical sounding "they eat because they are growing, rather than growing because they eat".

Notice that most of these hypothetical causal graphs describe processes internal to the organism and difficult to observe or intervene on, and not all that much is definitively known. This is what makes this a hard problem. It is doubly hard if one does not realise that one must think in these terms to make any progress.

I haven't read Taubes' books, but I have read some of his blog posts and here's how I understand this position. I'm not very certain that my understanding is correct, but maybe this will help.

He agrees the "simple thermodynamic" calories in - calories out = weight gain model is (necessarily) true. But he thinks it's misleading and isn't helpful, because it focuses on the (high) calories in and (low) calories out as the causes of weight gain, as if they were solely and directly influenced by deliberate behavioral choice. He says they are proximate, not ultimate causes, and are mostly determined by various complex metabolic states. And these states are in turn influenced, among other things, by the makeup of the diet - rather than just by its caloric value.

So if not conscious behavior, what determines calories in and out? For instance, various metabolic and hormonal states determine the level of hunger, food cravings, etc.

What his epiphenomenal claim means, if true, is that the causal graph doesn't look like this:

Decide what and how much to eat => Eat as decided => Lose or gain weight

But like this:

Eat something => Metabolic state changes depending on diet => Hunger levels and specific cravings change in response to metabolic state => Eating behavior changes in response to hunger.

And in particular:

Eat refined carbs => hunger levels rise, more food cravings => end up eating more => weight gain, sometimes in a runaway positive feedback loop leading to obesity.

On his blog he goes into a lot of detail about the biochemistry of hormonal signals relating to hunger, and to fat storage and release; I can't really follow those discussions.

This idea of calorie intake and expenditure being an epiphenomenon... Taubes certainly does say things that seem to suggest that, but what it would even mean for that to be true?

Calorie intake and expenditure are automatically regulated by the body, and in a healthy person, marginal increases or decreases in calorie intake will cause matching changes to both appetite and to energy expenditure, by changing body temperature, fidgeting, and other expendable metabolic processes. Large, forced decreases in calorie intake must cause either a balancing release of energy from fat cells, or a matching reduction in energy expenditure, but unfortunately, it's likely to be the latter. In that case, the energy expenditure comes from sacrificing metabolic processes that aren't really expendable, damaging health. Obesity can only occur if this regulatory process is broken somehow. It is more likely to be broken by a high-carbohydrate diet than by a high-fat diet. If it's broken in someone who's on a low-fat, high-carbohydrate diet, then switching to a high-fat low-carbohydrate diet is likely to fix it.

The previous paragraph is what I believe to be true. I don't know how well it lines up with what Taubes has said, but I don't care because Taubes is just a human. It does seem that he's failed to communicate it clearly, but if you're going to criticize him for that, the criticism should be delivered in the context of a clear restatement of the same position. If you're going to go around saying things that are incompatible with the previous, then please address it directly; everything you've said so far is at least one step removed, and it's frustrating because you keep saying things that aren't even wrong.

not even being coherent

Yes, but is it less coherent than the mainstream? Or even than a typical nutritionist that claims to be mainstream?

Prediction which follows from that hypothesis: People should be similarly worked up about exercise? (High intensity vs. low intensity, aerobic/anaerobic ratio, etc). I don't run into nearly as many people with strong opinions about this topic, so I think that this can't be the only factor at play...

Fascinatingly, diet is not on wikipedia's list of controversial topics EDIT: nm, corrected by /u/Nornagest here

But I think that you're right, and the reason people aren't concerned about exercise is that fewer people exercise. Everybody eats, and so a large number of mildly-nerdy-people have done at least a little research on diet, formed an opinion, and (to some extent) base their diet around that opinion. It's one of the few scientific topics that laypeople are deeply interested in, and one of the few topics that can make media headlines....and perhaps exercise makes fewer headlines because the market is smaller and thus it's harder to profit from it.

I think there's other driving factors too - why does the topic of vaccination enjoy similar polarization in some circles? Why the large number of people worried about GMO, pesticides, water fluoridation, drugs, etc? I think putting things into your body somehow inherently ties into our "purity" sense...thinking about threats to human bodily integrity instinctively sets off strong emotions. However, at least many of those topics have some public policy ramifications, while the impact of the the carb vs. fat debates on public policy is limited.

...and that's before you consider the whole problem of using conscious animals and of environmental impact, which I'm sure creates a negative halo effect by giving a few individuals instrumental incentives to believe that certain diets are bad for human health in addition to being bad for the environment / hurtful to animals. (Though I've got to say, every time I've talked about this with a LW crowd no one had that particular problem, which is impressive.)

every controversial issue has at least one unpleasant truth which people are subconsciously aware of (or afraid of) but reluctant to face.

Both sides of a controversy may assert that they are in possession of an "unpleasant truth" that the other side is afraid to admit to. Conspiracy theories work pretty well as "unpleasant truths", for instance; as do prejudices, eschatological or afterlife beliefs, and so on.

So that doesn't seem to be a good guide to who is correct when you're within the controversy.

Two separate points:

1) As a heuristic, that seems like rhetoric designed to create a bias towards certain viewpoints , not rationality. In every controversy there are two sides that believe different things, and often at least one side often believes that the other is missing some sort of "uncomfortable truth" which collapses their worldview. There's no a-priori reason to assume uncomfortable-truth-proposers are the correct ones in a given controversy.

2) There may or may not be be "uncomfortable truths" around obesity relating to its relationship to willpower, etc. However, that's not sufficient to explain why talking about the fine points of high fat vs. high carb diets should ignite controversy. If the title of this post was "Obese are fat due to X moral failure", I'd understand the controversy, but the outcome of the carb vs. fat debate won't negatively impact any demographic, except for various business interests and concerns about animal rights or environmentalism. (And that doesn't really seem to be the debate driver either)

How do people's identities get tangled up with a carb vs. fat position, and the question of whether or not a high-fat-low-carb diet allows for a higher caloric consumption without gaining more weight? At the face of it, the question seems specific and non-threatening - no threat of moral failure, no criticism... only the possibility that some people might benefit by changing their diet composition.

I believe Steve Sailer hypothesized that every controversial issue has at least one unpleasant truth which people are subconsciously aware of (or afraid of) but reluctant to face.

I would assume that if the theory is true, both sides have something they don't want to admit.

I wonder what percentage of the participants are obese/overweight and troubled by their obesity/overweight.

You also have the effect of non-overweight people who enjoy being sanctimonious or condescending.

Frankly, I suspect the uncomfortable truth here is that there is barely enough evidence for pick out hypotheses out of hypothesis-space much less test them, thus both sides are mostly bullshitting and afraid of getting called on it.

This is strange. Why is the model so simple? It's written nowhere that the human body must convert all calories to fat and must take all calorie deficits from fat. In the hypothetical situation where you eat X calories at 40% efficiency, switch to eating 0.5X calories and your body switchs to 80% efficiency, you end up eating half as much calories without changing your weight.

If you're going to argue that certain diets make it easier to eat less, why attack the "calories in, calories out" position like that (complain it's simplistic when it's true)? It's just going to confuse the hell out of your readers. Whether you're dieting, devising a product or competing at sports it helps to know what the goal is, because you can usually get to it in various different ways.

Edited for hopefully a bit more clarity.

Unless I'm wrong, there is a large chunk of the population who believe diets have some magical element that differentiates them from other diets. Atkins, from my limited understanding, involves a magical element, coming up with a sciency-sounding explanation for it.

Being reminded of obvious things isn't always useless. (For example, Stein's law “If something cannot go on forever, it will stop” is a tautology if you think about it, but...)