Blog | Wednesday, October 1, 2014

Diet research, stuck in the stone age

You cannot get a good answer to a lousy question.


Why prehistoric? Because it is long known and well established that dietary fats run the gamut from good to bad to ugly. No good diet should willfully exclude the monounsaturated fats and omega-3s in nuts and seeds and avocados. I’m pretty sure everybody not stuck under a boulder knows that.

There is ongoing debate today about specific effects of specific fats, but the wholesale cutting of dietary fat intake was pretty much yesterday’s news yesterday. The relevant concept today would be plant-based eating, which at the extreme of veganism, tends to be low in fat, but as an effect rather than an objective. This was not a study of a vegan diet.

The concept of low-carb is also terribly outdated, and was silly when it was first spawned. Everything from lentils to lollipops is carbohydrate. Why on earth would anyone want to treat such a vast expanse of the food supply as if it were just one thing? Sillier still, all plant food is a carbohydrate source. A truly “low-carb” diet is, of necessity, low in all plant foods, including vegetables, fruits, nuts, seeds, beans, and lentils along with whole grains. This is directly at odds with everything we know about diet and health across the lifespan.


The study didn’t even really ask this question. If you only read the headlines, you will believe it did, and frankly, most people will only read the headlines. I read the study, and before you start arguing with me, I invite you to do the same.



In contrast, baseline carbohydrate intake was 240 grams per day, so while fat intake was “trimmed” 5 percent, carbohydrate intake in that assignment was slashed 75 percent. This might have been billed “a study to compare a really big change from baseline diet to a really small change from baseline diet.” I suppose we can all guess why it wasn’t called that.

That would be bad and biased enough if the researchers had made any attempt to compare comparably good, or comparably bad versions of the two diets; but they did not. The “low-fat” diet was, for starters, not much lower in fat than the typical American diet, which as we all know, is basically crap. Shockingly, the fiber intake was virtually identical, at about 15 to 16 grams per day, in both groups throughout the study. You cannot possibly eat any variant on the theme of “good” low-fat, mostly plant-based eating and fix the fiber intake at that pitiful level. The only way to do that is to combine modestly low fat with preferentially crummy foods made mostly from refined starches and added sugars. The study did not provide this level of detail about the diets, but it’s clear that the low fat diet was (A) not low fat; and (B) rather crummy. So another title option was: “a comparison of the best low-carb diet to the worst low-fat diet we could come up with.” Again, I think it’s clear why they didn’t go with that one.


And so, the results were a foregone conclusion. Over the span of a year, obese people who ate less, lost more weight. And those who lost more weight had more improvement in their cardiac risk measures, which were mostly a mess in the first place due to obesity. Ta-da!


But I am an advocate of research that is fair, unbiased, and relevant in the real world. As the head of a clinical research lab, and the author of textbooks on research methods, I am an advocate of sound answers to sensible questions. This is a defense of sense, and good science. Neither of which was on display in this study. As best I can tell, neither was fairness, nor even honesty. The researchers themselves called their interventions “low-fat” and “low-carbohydrate,” and must have known from the start they were cooking those definitions over very different fires.




