I'm perplexed. Could I really be the only one who sees the great irony in the opening statement of this Mayo Clinic press release stating that higher calorie intake, as self-reported by those with memory loss, ages 70-89, is associated with greater mild cognitive impairment (MCI)? Under the title Overeating May Double The Risk Of Memory Loss the authors conclude "Cutting calories…may …prevent memory loss as we age." The study suggests that eating "too much" (more than 2,143 calories) may double the risk of memory loss.
Yes, the very people assessed to have the worse cognitive function reported the highest, sometimes extremely and unbelievably high calorie intakes. And as the press release video reveals, we're talking significant impairment (as in “Oh my, I've forgotten I was supposed to fly to New York yesterday" — oops!)
Even self-reported food intake using a validated assessment tool has its faults. (As in the Harvard study .) Being validated does not mean that the findings are real, that they reflect what was truly eaten. It merely addresses reproducibility. In this Mayo Clinic study, the only thing that was truly confirmed (as reported in the press release) is the degree of impairment, as assessed by more than one source. So we know participants are truly cognitively impaired, but we don't know with certainty how much they really ate calorically in the preceding year they were reporting on. Quite the population for accurately reporting, retrospectively, the amount they ate!
Maybe, given their MCI, they've forgotten how many portions they really consumed? Or perhaps they forgot that we typically don't report these things honestly.
The Joke is on Us
So here's my beef. The Mayo Clinic's press release, and subsequently the media outlets which picked it up, misled us. Even if my reasoning is off and all of the potential places where the science seems shabby were fully explained in the full study (which is yet to be released) there remains this problem—the media's conclusions suggest causation when at best we have an unexplained association.
The research summary states that higher calorie intake is associated with more cognitive loss (but does not necessarily cause it). So to then conclude, as most every article has, that we should be reducing our food intake, “cut out the chips” even, limiting our calories to prevent memory loss couldn't be more absurd! How unreasonable to manipulate us with these faulty one-liners, these irresponsible conclusions.
The Real Answer May Lie With BMI
The study controls for variables that might otherwise have confounded or confused the results. The researchers appropriately ensured that the finding, the increase in MCI with higher calorie intake, was not the result of such variables as diabetes, stroke, and, important to this argument, BMI. In other words, if I understand the press release and study abstract correctly, the increase in MCI associated with increased calorie intake at the highest intake levels, was not due to BMI. So BMI would not have been similarly increasing along with the cognitive impairment. Or, for that matter, with caloric intake.
So here's where I run into some difficulty. The study is stating that some, many individuals ages 70-89 years, are consuming > 2,000 to 6,000 calories daily, if we believe what they self-reported. And this is not linked with increasing BMI? If it isn't, that means people eating a rather extraordinary amount of food have no higher BMI than those at lower intakes. Soooo, if they are eating so much, but don't have higher BMIs, than how do we explain this?
There are several possible explanations. They could be expending more calories from exercise. Yet from the abstract, there was no mention of activity level—a major omission if we are assessing intake and making claims regarding the effects of intake without exploring output. Maybe it's exercise that's linked with MCI, for goodness sake, as exercisers would need to be eating at higher calorie levels. “Exercise Causes Cognitive Impairment.” Wouldn't that make for a headline!
Or, maybe there is some other medical explanation for such high intakes without resultant higher BMI. Are they malabsorbing—as in such conditions as celiac disease? This would result in nutrient deficiencies, which certainly may be responsible for cognitive losses.
Or maybe they have some thyroid condition, or cancer, not yet diagnosed, which may account for greater expenditure of calories, and may also impact cognitive function. I am no expert on memory loss—that I can say with certainty. But it appears the researchers have not done due diligence regarding their study and its conclusions.
In fairness, all the answers may be in the full research paper, yet to be published. Yes, I requested it, but was only presented with the abstract and the press release; even my questions regarding exercise were ignored.
Even referring to the higher calorie intake as “excessive” or "overeating", leaves me scratching my head—on what grounds? If you are more active than your peers at 75 years old—still playing tennis, walking regularly, golfing in your retirement years, even hiking as I've seen many a 70 and 80 year old do—wouldn't you need to be consuming more calories? Why should they be labeling this higher intake excessive, unless it is resulting in an undesirable weight increase outside of their normal range? But I didn't see this addressed in either the abstract or the press release.
And why should you care?
You, my readers, do not match the profile of the study participants in terms of age. But you are being irresponsibly told that lower calorie intake may prevent cognitive failure. And when it comes from a reputable establishment such as the Mayo Clinic, and sealed as a reality in the written word of such media outlets as the Wall Street Journal, Time Online, and others, you'll believe it.
You'll believe that higher calorie intake is detrimental—regardless of your caloric need. And then another study may arise (like the Harvard study) drawing similarly inappropriate conclusions, and you'll buy into those senseless conclusions, too. And soon you'll be so inundated with all this "science" that you'll be overwhelmed about what you can eat and what you should avoid and how much. See the problem?
What can you do? Don't be too quick to accept the written word as fact. Await a follow up study that might confirm findings. And be careful about where you get your information. Sure, reputable resources are better than sites promoting and selling something, with a financial interest in convincing you of the value of their words. But even seemingly solid institutions and individuals can draw the wrong conclusions. When in doubt, discuss such articles with those capable of shedding some light on the findings.
The unfortunate end result of early publication of scientific studies is a loss of trust. Studies that haven't yet made it for publication in peer-reviewed journals have no place in the hands of the public. Misinformation runs rampant, and as consumers of this information, we are left overwhelmed and confused. And it's a bad state of things when we can't trust science.