We have been pretty clear about our distaste for fad diets – we don’t really like even the notion of a “diet”, for that matter – and frequently try to debunk the malarkey and get back to basics: “eat food. not too much. mostly plants.”
In the current issues of Annual Review of Public Medicine, Drs. David Katz and Stephanie Meller (1) review the evidence for and against the most common mainstream diets – namely, the DASH diet, vegan and Mediterranean, as well as several incarnations of “low-[fill in blank]”. Did one diet come out on top?
The article by Katz and Meller (1) is truly worth the read (click here for full-text, if you’re lucky enough to have access). For those of you without access to a pricey site license OR limited time, we really liked this succinct review from Dr. James Hamblin at The Atlantic, so we decided to re-post some highlights (with our bold emphasis and two-cents thrown in) below…
Flailing in the swell of bestselling diet books, infomercials for cleanses, and secret tips in glossy magazines, is the credibility of nutrition science. Watching thoroughly-credentialed medical experts tout the addition or subtraction of one nutrient as deliverance—only to change the channel and hear someone equally-thoroughly-credentialed touting the opposite—it can be tempting to write off nutrition advice altogether. This month we hear something is good, and next we almost expect to hear it’s bad. Why not assume the latest research will all eventually be nullified, and just close our eyes and eat whatever tastes best?
The voices that carry the farthest over the sea of diet recommendations are those of iconoclasts—those who promise the most for the least, and do so with certainty (BURN!). Amid the clamor, Dr. David Katz is emerging as an iconoclast on the side of reason. At least, that’s how he describes himself. From his throne at Yale University’s Prevention Research Center, where he is a practicing physician and researcher, said sea of popular diet media is the institution against which he rebels. It’s not that nutrition science is corrupt, just that the empty promises of memetic, of-the-moment diet crazes are themselves junk food. To Katz they are more than annoying and confusing; they are dangerous injustice.
Katz and Yale colleague Stephanie Meller published their findings in the current issue of the journal in a paper titled, “Can We Say What Diet Is Best for Health?” In it, they compare the major diets of the day: Low carb, low fat, low glycemic, Mediterranean, mixed/balanced (DASH), Paleolithic, vegan, and elements of other diets. Despite the pervasiveness of these diets in culture and media, Katz and Meller write, “There have been no rigorous, long-term studies comparing contenders for best diet laurels using methodology that precludes bias and confounding. For many reasons, such studies are unlikely.
Among the salient points of proven health benefits the researchers note, nutritionally-replete plant-based diets are supported by a wide array of favorable health outcomes, including fewer cancers and less heart disease. These diets ideally included not just fruits and vegetables, but whole grains, nuts, and seeds. Katz and Meller found “no decisive evidence” that low-fat diets are better than diets high in healthful fats, like the Mediterranean. Those fats include a lower ratio of omega-6 to omega-3 fatty acids than the typical American diet.
Hooray for well-balanced vegetarian diets and removing the “bad” stigma from otherwise healthy higher-fat foods like nuts and seeds, fish and plant oils.
The Mediterranean diet, which is additionally defined by high intake of fiber, moderate alcohol and meat intake, antioxidants, and polyphenols, does have favorable effects on heart disease, cancer risk, obesity, metabolic syndrome, and “is potentially associated with defense against neurodegenerative disease and preservation of cognitive function, reduced inflammation, and defense against asthma.”
They also found carbohydrate-selective diets to be better than categorically low-carbohydrate diets, in that incorporating whole grains is associated with lower risks for cancers and better control of body weight. Attention to glycemic load and index is “sensible at the least.” Eating foods that have high glycemic loads (which Katz says is much more relevant to health outcomes than glycemic index—in that some quality foods like carrots have very high indices, which could be misleading) is associated with greater risk of heart disease.
See, whole grains are not evil! As Katz and Meller describe, limiting REFINED carbohydrates, i.e., “the white stuff”, is a sensible idea BUT scrapping quinoa, bulghur and other grains is unlikely to result in either sustained weight loss or long-term health benefits. Precisely why ketogenic diets are on our “don’t bother” list.
Finally, in a notable blow to some interpretations of the Paleo diet, Katz and Meller wrote, “if Paleolithic eating is loosely interpreted to mean a diet based mostly on meat, no meaningful interpretation of health effects is possible.” They note that the composition of most meat in today’s food supply is not similar to that of mammoth meat, and that most plants available during the Stone Age are today extinct.
Again, it’s about being sensible. See Jill’s previous post on the Paleo Diet for more information.
The ultimate point of this diet review, which is framed like a tournament, is that there is no winner. More than that, antagonistic talk in pursuit of marketing a certain diet, emphasizing mutual exclusivity—similar to arguments against bipartisan political rhetoric—is damaging to the entire system and conversation. Exaggerated emphasis on a single nutrient or food is inadvisable. The result, Katz and Meller write, is a mire of perpetual confusion and doubt. Public health could benefit on a grand scale from a unified front in health media: Endorsement of the basic theme of what we do know to be healthful eating and candid acknowledgement of the many details we do not know.
No Baloney’s advice? Stick to a simple, tried and true diet of… real FOOD. No magic wand or empty promises, just evidence-based conclusions and common sense! We always suggest sticking with minimally processed, whole foods – lots of vegetables and fruit, whole grains, nuts/seeds and (optional) lean meats and fish. We always come back to the 80-20 rule – 80% of your choices should be the best possible, 20% (or less) is your guilt-free, less-healthy-food wiggle room. Don’t waste your 20% with junk that doesn’t even taste good – we’re looking at you Cheez Whiz. Be mindful, enjoy your food, and put down the fork when you are satisfied.