The quality and quantity of calories both count

Among others, Gary Taubes has famously argued that calories don’t count. Perhaps the more nuanced version is that the quality of calories, not the quantity, is what counts. Mr. Taubes and I have discussed this, and agreed to disagree. Leaving aside Newton and laws of thermodynamics, there is the Twinkie Diet on my side: evidence that weight can be lost when calories are restricted, no matter how truly dreadful the quality of those calories. To give Mr. Taubes his due, most people in the real world gain weight, not lose it, by eating Twinkies.

My view is that the quality and quantity of calories both count. The quality of calories is the quality of the fuel that runs our bodies — it counts for that reason. The quality of calories also influences the quantity. While it may be that “no one can eat just one” chip, everyone can eat just one apple. Quality and quantity interrelate.

Dr. Robert Lustig has argued that excess sugar, and specifically excess fructose, is the one thing most importantly wrong with the modern diet; he and I have also agreed to disagree. Dr. Lustig has invoked high-quality science to demonstrate how fructose can harm our livers by causing fat accumulation there, and thus damage our health, in virtually all the same ways as alcohol.

But a paper just published in the journal Applied Physiology, Nutrition, and Metabolism demonstrates that under real-world conditions, a preferential focus on fructose may be unjustified. The investigators found no increase in liver fat over 10 weeks with sugar-supplemented diets, and no differential effects based on the kind of sugar. On the other hand, the study was funded by the Corn Refiners Association, and was likely developed with this very outcome in mind.

But even if this study is suspect, there are other reasons to doubt that fructose is our one true cause for worry. A recent study shows an association between sugar-free soda intake and diabetes. This may be a direct effect of sugar substitutes, or more likely because people drinking intensely sweet sodas of any variety tend to consume a diet higher in sugar overall. But at a minimum, the association is a precautionary tale about benefits to be expected from replacing the sugar in soft drinks.

More importantly, if Dr. Lustig is right, the much-revered T. Colin Campbell, who has implicated animal protein in our health ills, must be wrong. Our trouble can’t be all about fruit sugar if it’s all about animal protein, and vice versa.

If Dr. Campbell is right, then not only Dr. Atkins and Dr. Agatston, but also Loren Cordain, a respected paleoanthropologist emphasizing the prominent place of meat in our native diets, have to be wrong. If Cordain and others are right, then not only Campbell, but Barnard and and Esselstyn and the other ardent proponents of veganism are wrong.

If the most ardent proponents of a vegan diet are right, the proponents of the Mediterranean diet must be wrong.

And on it goes. The Center for Science in the Public Interest warns that excess dietary sodium may kill as many as 150,000 of us each year. A sophisticated analysis, based on three distinct computer modeling approaches, just published in the journal Hypertension, indicates that meaningful reductions in average intake of dietary sodium in the U.S. could save between 280,000 and 500,000 lives over the next decade. This suggests that CSPI’s argument may be slightly exaggerated, but is directionally correct. But if sodium is a major source of harm, then arguments that our only worry is meat, or fructose, or eggs, or carbs, or aspartame are all wrong.

I think there is a better explanation for all of this, and it’s one we’ve heard before, courtesy of the poet John Godfrey Saxe. Saxe wrote the most famous version of the parable “The Blind Men and the Elephant,” in which each of six blind men seeking knowledge of the beast take hold of a different part, from tail to ear, and reach a distinct conclusion. Saxe wrote that “each was partly in the right, and all were in the wrong.”

All were in the wrong not about the part, but about the sum of the parts. And so, too, for diet and health. I believe all of my expert colleagues have something worthwhile to contribute to our understanding. Where they err, in my opinion, is thinking that any one part of this story is the whole story.

There is no question that dietary patterns at odds with the fundamentals of what we know about the basic care and feeding of Homo sapiens are a major cause of the most egregious injuries imposed on modern public health. There are many minor deficiencies and major excesses contributing to the adversities of our dietary intake.

But no one thing is wrong with the prevailing American diet, and no one-nutrient-at-a-time remedy will right it any more than a single part represents the whole elephant in the room. We need to see that elephant, and develop a better recipe.

David L. Katz is the founding director of Yale University’s Prevention Research Center

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