“Don’t you realize that fat is unhealthy?” is often asked by concerned people/concern trolls in FA spaces. I came upon a variation of it that’s worth addressing as the first comment here. The commenter responds to Tanteterri’s criticism of “everyone knows” assumptions by saying, “Academia is a cumulative effort. Current research is based on old research. If every older point of data suggests that being overweight is unhealthy, why not start on that foundation?”
In other words, aren’t “everyone knows” memes* about fat based on solid research?
Well, no, not always.
Unfortunately, stuff that “everyone knows” is often not seen as worth studying, or if it is studied, not all interpretations of the results are looked into because we “know” what explains the results. Often, researchers and doctors assume that these “everyone knows” facts have been studied even though they have not. See, for example, the NY Times article and NEJM article linked to by Ragen here.
From the NY Times article:
Dr. Allison [director of the Nutrition Obesity Research Center at the University of Alabama at Birmingham] sought to establish what is known to be unequivocally true about obesity and weight loss.
His first thought was that, of course, weighing oneself daily helped control weight. He checked for the conclusive studies he knew must exist. They did not.
“My goodness, after 50-plus years of studying obesity in earnest and all the public wringing of hands, why don’t we know this answer?” Dr. Allison asked. “What’s striking is how easy it would be to check. Take a couple of thousand people and randomly assign them to weigh themselves every day or not.”
Yet it has not been done.
If these “everyone knows” memes hold up to scientific scrutiny, there’s nothing wrong with scientists using them**. If they’re just folklore and have never actually been tested, they have no place in science.
*Used in Dawkins’ “unit of information” sense, not the “thing that gets passed around on the internet” sense.
**Using them for what is another question. If they find a particular practice does help people lose more weight or lose weight faster, but have not figured out a way for most people to maintain that loss, that practice has limited utility to the general public. On the other hand, that knowledge might lead to a better understanding of the system the body uses to regulate weight, which is a perfectly good use of that information.