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David Katz, M.D.

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Chewing on the Best Diets

Posted: 01/10/2012 7:43 am

As you likely know, U.S. News and World Report released a list of "best diets" to coincide with the annual bumper crop of weight loss resolutions as the new year begins. I was privileged to be one of the 22 judges.

We worked in isolation of one another, so none of us knew what the others were thinking. This is good in some ways, because our opinions were unbiased by one another's passions or pet peeves. But it is bad for the same reasons. Anyone who has seen any version of 12 Angry Men knows how potent, and valuable, an exchange of ideas can be.

Be that as it may, we submitted our reports independently. Each of us based our judgments of each of 25 diets in seven different categories on published papers, online materials, and personal clinical experience. U.S. News and World Report submitted very helpful summaries to us, including links to recent and important studies -- but we were encouraged to go beyond this material, and I am confident all of us did.

I get the sense we agreed more than we disagreed, and am fairly comfortable with most of the outcomes. That said, the results represent the panel's consensus and don't correspond perfectly with my worldview -- nor, I suspect, with that of any of my colleagues.

Overall, the rankings were a ringing endorsement of balanced, sensible approaches to weight control. No diet based on a gimmick or on wild distortions of a healthful dietary pattern scored well. Those diets that did score well were generally conducive both to losing weight and finding health. Big winners included Weight Watchers, which came in first for both weight loss and ease, and DASH, a diet developed at the NIH for blood pressure control and has since shown to confer other health benefits. The Mediterranean diet and the low-fat, plant-based diet developed by my friend Dean Ornish placed highly as well.

However, different diets did come in first for health, weight loss, diabetes and heart disease -- and personally, I find that a bit silly. Weight loss by healthy means is among the most important ways of reducing risk for diabetes and heart disease. A diet that reduces diabetes risk reduces heart disease risk. A diet that reduces risk of heart disease and/or diabetes, two of the leading public health perils of our time, is obviously good for health. A diet cannot be good for health unless it reduces the risk of heart disease and diabetes. Diets that help prevent inflammation fight heart disease, diabetes and cancer.

I trust you see where this logic leads. A good diet is a good diet, period. A good diet is conducive to health promotion, the prevention of chronic disease and the control of weight. A good diet is sensible, balanced, pleasurable and sustainable. And a good diet is suitable for the whole family so that while you are losing weight on the "____" diet, you don't have to wonder: What the heck are my kids eating?

This same logic extends from the level of diet, to foods, to nutrients. What's good for us is good for us, and what isn't... isn't. Unfortunately, physicians -- who historically are not well-trained in nutrition -- have confounded this issue pretty badly. Cardiologists have cautioned hypertensive patients against sodium intake, often overlooking the fact that an excess of sugar, starches and calories leading to weight gain would cause blood pressure to go up. Diabetics have been cautioned against sugar, but they are prone to hypertension and need to be mindful of sodium intake as well. Patients with high cholesterol have been counseled to avoid trans fat, saturated fat, and dietary cholesterol -- but excesses of sugar and salt can propagate vascular injury as well.

Health cannot be achieved, and with the exception of deficiency syndromes, disease cannot be avoided- one nutrient at a time. The overall nutritional quality of a food is what truly matters. Broccoli is not highly nutritious because it is free of trans fat; broccoli is highly nutritious... because it is broccoli!

And, of course, a diet is made up of foods. A high quality diet is made up of high quality foods -- and we do, indeed, have evidence -- in 100,000 people -- that such dietary patterns are associated with both weight control and better health overall: less cardiovascular disease, less diabetes and less risk of dying prematurely of any cause.

So we can, and should, establish some logical parameters for gauging the quality of a diet. We can, and have, devised metrics specific to that mission -- with newer and better ones in the works. But can we actually say what diet is "best"?

I have weighed in on that topic before, and basically said -- no. We have abundant evidence to support a basic theme of healthful eating, and almost none to say which of the several reasonable contenders (Asian, vegan, Mediterranean, etc.) is truly best. The logistics of a decisive trial to tell us which diet is truly best, if indeed one is, are sufficiently daunting that we may confidently anticipate doing without such evidence for the long term. Would you be willing to be randomly assigned to a vegan diet, a Mediterranean diet or a Paleolithic diet for the next 30 years? Unless a whole lot of people answer "yes," the trial we need cannot be done.

In some ways, that's good, because it means that while we do have a very well-substantiated, evidence-based theme of healthful eating -- conducive to weight control, chronic disease prevention and vitality -- we are left with considerable room for variations on that theme. There is benefit in such doubt, because it allows for customization and the indulgence of your personal preferences and priorities. You are, as you should be, the boss.

But let's be clear, there IS a theme -- and though you are the boss, you abandon the theme at your likely peril, at least in the long term. The fundamentals of the theme have been captured by Michael Pollan as well as by anyone: "Eat food, not too much, mostly plants."

Eating food means real food. Pronounceable food. If it glows in the dark, you probably shouldn't eat it. The longer the shelf life of the product, the shorter the shelf life of the person eating the product. Out just today (Jan. 9, 2012) is a paper suggesting that eating real food reduces the risk of ADHD in our kids, while highly-adulterated foods have the opposite effect. Science, meet intuition!

"Not too much" might seem like hard advice to take, but quality control provides for quantity control. Many processed foods are of the "betcha' can't eat just one" variety -- and specifically engineered to be so. Wholesome foods -- an apple, for instance -- are of the "betcha' won't eat more than one" variety. In fact, I've recently learned of a mom who lost 115 lbs. due almost entirely to use of the NuVal system in her supermarket, and simply trading up to more nutritious choices in each aisle. By addressing quality, quantity and weight mostly took care of themselves.

"Mostly plants" is pretty straight-forward. An emphasis on plant foods is evident in almost all diets associated with both weight control and health, and is, into the bargain, important for the health of the planet. Ultimately, being thin and healthy won't count for much if we don't still have a viable planet to call our own.

As noted, Weight Watchers won the laurels in several of U.S. News and World Report's categories: best for weight loss, best commercial program and easiest/most convenient. I am a proponent of Weight Watchers because their programming clearly works for weight loss (on the U.S. News site, each diet now has statistics attached to it, and those reporting Weight Watchers worked for them outnumber those who say it didn't by two to one; the ratio is just about the converse for every other diet on the site!), is sensibly aligned with healthful eating and provides the structural support many people need.

I believe, however, we can do even better -- building skill power systematically and comprehensively to facilitate lifelong health and weight control, while addressing the needs of all family members at once. A program I have helped develop, Weigh Forward, is an example. I also see opportunities for customizing variations on the theme of weight control based on genetic testing, especially for those who find they are unusually weight loss resistant -- an idea that is just now ripening into real utility.

As we size up best diets at the start of a new year, we can celebrate the winners -- but note that too many of us are still losing. A majority of adults in the U.S. are overweight or obese -- as our far too many of our kids. Our best efforts to date are not good enough.

What would truly be best is modifying the world -- so that eating well and being active simply prevailed. While waiting for that change -- or better, while working for it -- the best diet is bounded by considerations of not just losing weight, but finding health; not just you, but your family; not just now, but lifelong. Within the bounds of that theme, there is plenty of latitude for you to be the boss, and choose the best way forward for yourself and your family. Out of those bounds is a whole world of hucksterism and potential hurt. So I, and 21 other judges, encourage you to play inside the lines.

-fin

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Dr. David L. Katz; www.davidkatzmd.com
www.turnthetidefoundation.org

 

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