Blog | Monday, September 14, 2015

Chewing the fat, again

Among my numerous colleagues, friends, and correspondents are more than a few who circulate every abstract, however obscure the source, suggesting that saturated fat has been fully exonerated, or that everything we ever thought we knew about dietary fat, health, and weight has been utterly renounced.

I confess that to some degree, I engage in counter-measures, circulating studies that show rather the contrary. Generally, my interest is balance and the weight of evidence, so I will circulate any study I consider important, whatever the conclusions. But to the extent that I represent opposition to the inclinations du jour (or du news cycle, which lasts much less than a whole jour, these jours), it is not, by any means, because I have a low-fat chip on my shoulder. Rather, as I have indicated before, I have little tolerance for the Newtonian nonsense of New-Age nutritionism: for every dietary trend, fad, or fashion, an equal, opposing, reactionary trend, fad, or fashion.

So it is that when cutting fat let us down, mostly because we approached the enterprise as a pack of gullible nincompoops, we didn't thoughtfully reconsider the proposition of mono-nutrient fixations. That might have been genuinely constructive, but at odds with the Newtonian impulse. We opted for the latter, an equal, opposite, reactionary boondoggle. Decades later, the cycle has repeated many times, and here we are, propelled this way and that by Newtonian inertia, awash in hyperendemic obesity and chronic disease, accompanied by massive food industry profits.

This, then, is the prelude to brief remarks about two recent studies that rebut many of the currently fashionable rebuttals about dietary fat.

The first was a brief, metabolic ward study by perhaps the world's leading authority on energy balance, Dr. Kevin Hall at the National Institutes of Health. The timing was somewhat ironic, given the recent, high-profile implosion of an effort overseen by other scientists, purportedly devoted to the elucidation of energy balance. That, however, is another story, already told.

Dr. Hall has developed sophisticated, and influential energy balance equations that elaborate often-neglected nuances, such as the fact that the calories required to maintain weight decline as weight declines. This, by the way, accounts for the notorious “weight loss plateau“ on which so many dieters land, even as they profess their on-going adherence to the program. Their claims are legitimate, and Dr. Hall's equations validate them.

Dr. Hall's study was both small, and of short duration, but rigorously controlled. It compared isocaloric reductions in dietary fat versus dietary carbohydrate, and showed that body fat content declined significantly more with restriction of dietary fat. This seems a quaint throwback to what we thought we knew before we learned that everything we thought we knew was a big fat lie, or a big fat surprise, but it's not. It's entirely current, meticulous research.

The second paper is one of those systematic reviews and meta-analyses we can't seem to get enough of these days, and of which we arguably get too many to propagate anything other than perennial confusion. In any event, this review, by the widely respected Cochrane Collaboration, concluded that reductions in the percentage of total calories from fat lead consistently to reductions in body fat and body weight, too. This also seems to fly in the face of what we now prefer to think about what we once thought we knew.

I note these two publications partly because they are, indeed, both noteworthy. But I note them in particular in the service of balance, and better hopes for nutritional science than a never-ending sequence of misguided action followed by errant reaction.

Science is a method for answering questions; it is, in essence, a tool. A tool is never much better than the service to which it is called. A hammer, for example, is a perfectly good tool, but a dubious choice for opening windows, although it would do the job. You might use a microscope for diagnosis the next time your toaster won't work, and you may even notice formerly undetected flaws in its façade. You are unlikely, however, to discern at high magnification the fact that it isn't plugged in.

I am not at all interested in a resurrection of a preferential focus on wholesale dietary fat restriction. We should long since have recognized that questions about this or that macronutrient and weight are rather like the use of a hammer to open a window. An outcome is generated, and mums the word about the shards of glass all over the floor.

In the real world, health, weight control, and lifelong vitality are achieved on diets that vary considerably in macronutrient composition, but that all adhere to the same basic theme: wholesome foods, in sensible combinations, plant foods predominating. A vast array of research evidence from diverse sources, including randomized controlled trials, attests to the same. Alas, it just does not seem to satisfy our Newtonian impulses, or penchant for vituperations, religiosity, and procrastination.

We know how to eat well, for weight control and health, and sustainability; we just don't want to swallow it. We would rather, it seems, just keep chewing indefinitely, on fat, or carbs, depending on your palate, and the news that broke 8 minutes ago.

David L. Katz, MD, FACP, MPH, FACPM, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care. He is a board certified specialist in both Internal Medicine, and Preventive Medicine/Public Health, and Associate Professor (adjunct) in Public Health Practice at the Yale University School of Medicine. He is the Director and founder (1998) of Yale University's Prevention Research Center; Director and founder of the Integrative Medicine Center at Griffin Hospital (2000) in Derby, Conn.; founder and president of the non-profit Turn the Tide Foundation; and formerly the Director of Medical Studies in Public Health at the Yale School of Medicine for eight years. This post originally appeared on his blog at The Huffington Post.