Gary Taubes

Ok. I obviously don't have time to go through this list, but I can say that we (NuSI and Stuart Buck, the director of research at the Arnold Foundation) recently tried to assess all the relevant studies to see if any of them settled the energy balance vs. carbohydrate hypothesis definitively. Our list of the relevant studies is posted at NuSI along with an assessment of each trial. Here's the URL: http://nusi.wpengine.com/wp-content/uploads/2012/09/Summary-of-Diet-Studies-Condensed.pdf

Our assessment was that not a single one of these trials was even vaguely definitive. Here's the summary of our analysis: http://nusi.org/the-science/review-of-the-literature/#.UJF0qWkiH7E

One way or the other, this is a question that deserves far better experiments and a much higher quality of science to settle. This is what NuSI is planning to do. I'm open to the possibility that I'm dead wrong about this (doubt it, but it's possible) so the argument is let's get the best possible research done and resolve these questions with as little ambiguity as the real world allows. Ideally in ten years we'll have nothing to argue about.

I think calories in/calories out is simply the wrong paradigm to understand obesity and so meaningless. If someone gets fatter, they have to take in more calories than they expend. The same is true when gets kid taller, when people put on muscle instead of fat, etc. Focusing on calories tells you nothing about cause -- why one person puts on fat, another grows taller, one does both, etc.

I've been thinking once again about how to clarify this and I've come up with a couple of ideas. For one, I'll use sugar as the example because that's supposed to be the subject today. Imagine we have a pair of identical twins. Say 18-year-old boys. Every day we measure their energy expenditure and every day we feed them exactly how many calories they expend. So we match calories in to calories out. They get both the same diet with one exception: one gets 300 calories of sugar or HFCS where the other gets 300 calories of a different carbohydrate or of fat. Then we continue this feeding experiment for the next 20 years or so. (Because this is a thought experiment, we don't have to worry about the ethical issues or Institutional Review Boards.)

If you believe obesity is about calorie-in-calories-out and that's the only thing that matters, then both twins are going to end up exactly the same weight with exactly same amount of fat on their body and they're both going to end up expending the same amount of energy. If you believe that the hormonal/metabolic effect of different nutrients is the key factor, then the sugar in the diet of one twin is going to effect his insulin signaling, hepatic (liver) fat production and accumulation, etc, and possibly his fuel partitioning. This twin will end up with more fat, and maybe lower energy expenditure as well. (He or she can't end up weighing more, because we always match calories in to calories out.) The way they partition fuel into storage or oxidation will have changed significantly because of the change in macronutrient composition.

Now if we do the same experiment, but fix the calories in at whatever the twins we're expending at the beginning of the experiment (rather than adjusting it to the expenditure day by day) then the sugar-fed twin is likely to end up fatter as well as heavier because now the partitioning of fuel to fat instead of oxidation can cause this twin to both get heavier and expend less, and so go into positive energy balance.

And if these twins were allowed to eat as much as they wanted, the twin eating the sugar diet might crave more food to compensate for the loss of calories into the fat tissue and the greater need of a larger body.

Finally, imagine we do the same study with 10,000 twins or 100,000 twins. Half get the diet without sugar and half with. The population that gets the sugar, according to this hypothesis, would have more obese twins, more diabetic twins, etc. despite, again, total calories consumed being equal.

Now think of the opposite experiment for weight loss, and you can see why I think calories in/out is meaningless. We could match calories in a pair of obese identical twins and change the macronutrient composition in such away that one twin mobilizes fat from the fat tissue and oxidizes it and the other doesn't. So one twin will lose weight and be in negative energy balance if we allow that to happen and do so on the same number of calories that keeps the other twin as fat as ever and in energy balance.

Does this make sense?

Also made my day. thanks.

That's an interesting question. As you may know, I've recently co-founded, with Dr. Peter Attia, the Nutrition Science Initiative (NuSI.org) to fund and facilitate experimental research that should resolve, we hope, some of these controversies. The problem with this business is that because we have humans as subjects and we live in the real world, ideal studies cannot be done.

One ideal study, for instance, capable of falsifying the carb hypothesis would be to isolate 50,000 identical twins in a setting where we can completely control there diets -- along the lines of the thought experiment I discussed above. Randomize one half of the twin pairs to a standard American diet and one half to a very low carbohydrate diet. Give them no choice but to eat the diets. Say we put each half in a different town and they live there for the rest of their lives and they can only eat the food we supply. Run it out for 20 years and see what happens. If the half eating the low-carb diet is just as fat, diabetic, atherosclerotic, etc. as the half eating the standard American diet, that does a pretty good job of falsifying the hypothesis. If we want to control for calories, we make sure the twins eat the same amount of calories in each town.

Now this is obviously never going to happen. So what can we do in the real world. One of the first studies we want to do will be a rigorous test of the two competing hypotheses -- energy balance vs. carbs/insulin. The idea is similar to what I discussed above in the calories-in/calories-out question and I actually discuss this experimental design in the afterward to the paperback of Good Calories, Bad Calories.

Take as many overweight/obese subjects as we can, isolate them in a metabolic ward, feed them a standard American diet for a month say, get them weight stable and measure their energy expenditure. Then randomize into two groups. Both get exactly the amount of calories that they're expending when weight stable on the SAD. One, though, continues to get the SAD and the other gets a ketogenic/Atkins diet, which can be thought of as a dietary tool to maximally reduce insulin levels. Now run it out for as long as we can before the subjects rebel -- probably two to three months -- measuring energy expenditure regularly, fat mass at the end of the study, and nutrient balance. If they two groups expend the same amount of energy, and have the same fat mass at the end of the two months, that would be a pretty good refutation of the alternative hypothesis. If the low-carb group expends significantly more energy and loses fat in comparison to the SAD group, that would be a pretty good refutation of the conventional energy balance wisdom.

Now here's the problem: in both cases, there would be ways to explain the observations so that they don't actually falsify the less favored hypothesis. This again is a problem with the real world. We'd have to keep doing experiments until eventually even the avid supporters of one hypothesis just decided it was untenable. But as Richard Feynman has said, science isn't about proving or disproving hypotheses, it's about saying which is more or less likely to be true. If we do the right experiments and they're designed correctly -- and this is what NuSI hopes to facilitate -- eventually we'll be able to say for certainty which one of these two hypotheses really is very much more likely to be true. And we'll have to settle for that, until someone thinks of yet another test that should be done.

Short answer is I think they're all better than sugar/HFCS and there's not nearly enough data -- randomized controlled trials -- to show whether they are deleterious on their own. The evidence is just poor and the observational studies linking diet sodas to obesity/diabetes are meaningless, because they're, well, just observations and don't say anything about cause and effect. I did a short New York Times Magazine piece on artificial sweeteners about a year ago and concluded that the stevia compounds are probably the best, in that they're natural and have a long history of use. Here's the link: http://query.nytimes.com/gst/fullpage.html?res=9901E0D71E31F931A35753C1A9679D8B63 That said, last time I had a Diet Coke I got a headache the likes of which I can't remember having and so haven't touched the stuff since and that was about four years ago.

This is me.

Hmm, other than my faith in the democratic process?

I've been traveling the last 72 hours so it's not all that meaningful, but I can tell you that I have eggs, sausage and bacon pretty much every morning of my life, and avoid, for the most part, refined grains and starches. My wife's a mostly vegetarian, so we tend to make our own dinners. I'll cook some meat or fish and eat it with a green vegetable that she also eats. As for the kids, well, that's a constant struggle. I don't want to be a food zealot with them, but they do consume significantly less sugar than most of their peers. As for tonight, I'm off duty. We'll probably let them eat three or four pieces of candy and then throw most of the rest out after they go to sleep. I'll direct them to the Snicker's and Reese's peanut butter cups because that's what I'd be eating -- and might have a few small bites -- if I had my choice. While I mostly avoid refined grains, sugar and starches, I'm not completely rigid about it because my weight is fine and I'm healthy. If I found my weight was creeping back up, I'd get a lot more rigid.

That Alzheimer's associates with diabetes and obesity suggests there's something to it, and there's good evidence that insulin and insulin resistance are involved in the disease state. I discuss that science (and get some of it wrong) in Good Calories, Bad Calories. Researchers I respect do go for the type three diabetes notion, but I'd say it's still preliminary so bordering on hyperbole. As for silverhydra's comment below, the primary Alzheimer's researchers tend to all have their different opinions on causal factors in the disease state, even down to the roles played by amyloid beta and tau tangles. One advantage a journalist in this business is the ability to speak to everyone in the field, or all the major players, and try to make some sense about how the evidence supports the different biases. Whether this is enough to compensate for the obvious lack of expertise or training that the journalist brings to the issue (whether me or Mark Bittman or Gina Kolata or any other) is always an open question and a matter of opinion. If we always had to defer to the authority of primary researchers, then we'd better hope the primary researchers are doing a better job in Alzheimer's research than they've done in, say, nutrition and obesity.

I'm obviously a big fan as I think the paleo movement will go along way to getting the conventional wisdom changed. There are some tremendously smart people pushing the Paleo movement and they've raised issues of mechanisms that are intriguing and that go far beyond what I've discussed in my books. I'm hoping that one role of NuSI will be to help elucidate and test these mechanistic questions as well.