Diet, and Delusions of Evidence

By David Katz

Our perennial pseudo-confusion about diet- and pseudo-confusion, it is– is actually fueled by two parallel delusions, running in opposite directions. The first is that every opinion about diet changes the facts about diet; it does not. This delusion operates as if bias, preconceived notion, having the answer before asking the question, or having something to sell – is fully commensurate with expertise and the weight of evidence.

The second, opposing delusion is that every opinion about the evidence about diet changes the standard of “sufficient evidence.” It does not. This contention harbors the view that any amount of evidence can be dismissed as inadequate or even absent by those who find the message in it inconvenient.

Perhaps, then, there is a third delusion, too – that the two delusions above can co-exist. They cannot. If either is right, the other cannot be. There is no way that the assertion of a non-expert opinion at odds with, or absent any meaningful evidence can be “enough,” in a world where a vast aggregation of consistent evidence can be dismissed as inadequate or absent by those choosing to ignore it. At worst, a thinking population is obligated to pick one of these. At best, we should renounce them both for the nonsense they are.

I have addressed the matter of dietary pattern, the fundamentals consistent with the basic care and good feeding of Homo sapiens, many times before- so let’s focus here on those delusions of evidence.

When convenient, evidence that would be inadmissible in any other field is routinely hyperbolized into dietary gospel. The current fascination with the ketogenic diet, for instance, essentially resurrects the Atkins proposition under a new rubric. It is based not on a shred of evidence that the diet is sustainable over time, or good for people if so. It is based entirely on short-term improvement in the metabolic profiles of obese people with and without type 2 diabetes. But since almost anything that induces short-term weight loss improves metabolic profiles in obese people- including cocaine use, cholera, and tuberculosis- that hardly rises to the level of relevant evidence for population-wide dietary guidance.   Read MORE