Among the more popular and redundant provocations of pop culture, New-Age nutrition is to question the basic merit of "the calorie." There is something of a cottage industry in this particular brand of iconoclasticism, and for some of us, the challenge of keeping pace with it to dispense rebuttals. I am one of those.
The rebuttals routinely invoke Sir Isaac Newton, and it is in just such context that Newton is most apt to join conversations about, if not at, dinner. Newton's First Law of Thermodynamics asserts, essentially, that energy can neither be created nor destroyed in any closed system -- it has to go from somewhere to somewhere else. Energy and matter can be interconverted -- as is the case when the energy represented by calories is converted to the smaller (glycogen) or the larger (fat) of the body's energy reserve depots.
Arguments against the fundamental utility of the calorie to human energy balance, and weight control, really do devolve to arguments against Newton and this basic law. Of course, food varies in quality as well as quantity, as does all fuel. Natural gas, for instance, burns cleaner than coal in general; and wood burns differently still. Those differences matter, but equal quantities of stored energy in gas, coal, oil, or wood could be used to generate comparable amounts of heat- along with smoke of varying composition.
Similarly, the fuels on which our bodies run vary -- and all of those variations matter. The quality of the fuel for the human machine is one of the most critical influences on human health across a lifetime. Nutritional variation is in turn responsible for variation in hormonal responses, notably insulin; the ease of conversion of calories to either muscle or fat; and the amount of eating required to achieve fullness, or satiety. These effects all matter -- just as it matters whether the gasoline in your car does or does not contain lead.
But the amount of gas in your tank matters, too -- and so does the number of calories that go down the hatch each day. Studies show quite clearly that independent of the quality of calories, the quantity influences weight. We humans vary even more markedly than such attributes as the fuel efficiency of vehicles, but we are all still subject to laws bigger than us. The laws of thermodynamics are among those.
So I have long thought that to be Sir Isaac's niche in modern nutrition. It turns out, though, I was wrong.
The rather vapid answers engendered by fatuous questions about calories prove a minor concern compared to the larger trends in modern nutrition. Those trends involve moving continuously from one scapegoat or silver bullet to another. When we allegedly cut dietary fat (we never really did) and failed to get uniformly thin and healthy, we never considered that we might have cut fat "badly." We never considered that the advice had really been about eating more spinach, not Snackwell cookies. Instead, we renounced cutting fat as a boondoggle and moved on to the next.
In other words, we were overcome by another of Newton's laws -- the Third Law of Motion. This is the one that states: for every action, an equal and opposite reaction.
Now let's be clear, the law does NOT say anything about a thoughtful reaction. It makes no reference whatsoever to reflection, reasoning, or interpretation. The reaction in question is not temperate, moderate, or well-informed. It is not judicious, cautious, or wise. It is equal, and opposite.
That explains almost everything we need to know about modern nutrition. We cut fat, or didn't, and if we did, we did it badly. That didn't go too well, so we had an equal and opposite reaction: We cut carbs. Look around to see how well that turned out.
Back in the day, we fell in love with adding essence of oat bran to every food imaginable. Now, we are in love with repudiating gluten. Equal and opposite. We vilified saturated fat and ignored our increasing intake of sugar; now we vilify sugar and feel obligated to canonize saturated fat. Equal and opposite. Arguments for plant-based eating attract legions of devout adherents, precipitating the recruitment of equal and opposingly carnivorous legions.
Newton asserted that this is how unthinking objects moving through space would behave. He never said anything about them getting anywhere.
One would like to think, or at least wish, that we Homo sapiens might outperform the inertia of unthinking lumps traversing the ether. But the evidence of modern nutritional epidemiology is very much to the contrary. We, too, are going nowhere.
Given the stakes, this is unacceptable. Application of even those limited articles of nutrition on which we could all agree, invoking robust evidence, would suffice to eliminate fully 80 percent of the massive burden of chronic disease and premature death in modern society.
Apparently all that stands between us and that luminous prize is the capacity to learn from the follies of history, a willingness to accept fundamental laws of physics, and the aptitude to outperform a block of flotsam floating through space. In other words: The situation is hopeless.*
*Or not. If you have had enough of this nonsense, here is what I think we truly do know about the basic care and feeding of Homo sapiens, both for losing weight, and finding health. And on the chance that leaves you unconvinced, here is a review in the Lancet by my friend and colleague, Dr. Frank Hu (and others), reaching much the same conclusion. Here is a batch of free programming to help you get there from here, and here is more information about the world's first nutrient profiling system -- now in over 2,000 supermarkets throughout the U.S. -- to correlate with both total chronic disease risk and all-cause mortality. And into the bargain, my latest book, Disease Proof, is potentially quite helpful, too. Unless you prefer pixie dust and moronic morsels du jour, in which case it won't help you at all. It's a moronic morsel-free zone, which, of course, will reliably keep it off the best-seller list. Not to worry -- I have a day job.
Dr. David L. Katz has authored three editions of a leading nutrition textbook. He is editor-in-chief of the peer-reviewed journal, Childhood Obesity, and President of the American College of Lifestyle Medicine. He is the author of Disease Proof, and most recently, of the epic novel, reVision. Other than that, he spends his time floating through space, hoping not to bump into something.