Weight loss information has a very poor signal to noise ratio - too many myths and assumptions are elevated to presumed fact (via the NY Times)
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.
Instead, people often rely on weak studies that get repeated ad infinitum. It is commonly thought, for example, that people who eat breakfast are thinner. But that notion is based on studies of people who happened to eat breakfast. Researchers then asked if they were fatter or thinner than people who happened not to eat breakfast — and found an association between eating breakfast and being thinner. But such studies can be misleading because the two groups might be different in other ways that cause the breakfast eaters to be thinner. But no one has randomly assigned people to eat breakfast or not, which could cinch the argument.
So, Dr. Allison asks, why do yet another study of the association between thinness and breakfast? “Yet, I can tell you that in the last two weeks I saw an association study of breakfast eating in Islamabad and another in Inner Mongolia and another in a country I never heard of.”
“Why are we doing these?” Dr. Allison asked. “All that time and effort is essentially wasted. The question is: ‘Is it a causal association?’” To get the answer, he added, “Do the clinical trial.”
He decided to do it himself, with university research funds. A few hundred people will be recruited and will be randomly assigned to one of three groups. Some will be told to eat breakfast every day, others to skip breakfast, and the third group will be given vague advice about whether to eat it or not.
As he delved into the obesity literature, Dr. Allison began to ask himself why some myths and misconceptions are so commonplace. Often, he decided, the beliefs reflected a “reasonableness bias.” The advice sounds so reasonable it must be true. For example, the idea that people do the best on weight-loss programs if they set reasonable goals sounds so sensible.
“We all want to be reasonable,” Dr. Allison said. But, he said, when he examined weight-loss studies he found no consistent association between the ambitiousness of the goal and how much weight was lost and how long it had stayed off. This myth, though, illustrates the tricky ground weight-loss programs have to navigate when advising dieters. The problem is that on average people do not lose much – 10 percent of their weight is typical – but setting 10 percent as a goal is not necessarily the best strategy. A very few lose a lot more and some people may be inspired by the thought of a really life-changing weight loss.
The linked article in the NEJM - unfortunately behind their paywall.
Myths, Presumptions, and Facts about Obesity
Krista Casazza, Ph.D., R.D., Kevin R. Fontaine, Ph.D., Arne Astrup, M.D., Ph.D., Leann L. Birch, Ph.D., Andrew W. Brown, Ph.D., Michelle M. Bohan Brown, Ph.D., Nefertiti Durant, M.D., M.P.H., Gareth Dutton, Ph.D., E. Michael Foster, Ph.D., Steven B. Heymsfield, M.D., Kerry McIver, M.S., Tapan Mehta, M.S., Nir Menachemi, Ph.D., P.K. Newby, Sc.D., M.P.H., Russell Pate, Ph.D., Barbara J. Rolls, Ph.D., Bisakha Sen, Ph.D., Daniel L. Smith, Jr., Ph.D., Diana M. Thomas, Ph.D., and David B. Allison, Ph.D.
N Engl J Med 2013; 368:446-454January 31, 2013DOI: 10.1056/NEJMsa1208051
Many beliefs about obesity persist in the absence of supporting scientific evidence (presumptions); some persist despite contradicting evidence (myths). The promulgation of unsupported beliefs may yield poorly informed policy decisions, inaccurate clinical and public health recommendations, and an unproductive allocation of research resources and may divert attention away from useful, evidence-based information.
Using Internet searches of popular media and scientific literature, we identified, reviewed, and classified obesity-related myths and presumptions. We also examined facts that are well supported by evidence, with an emphasis on those that have practical implications for public health, policy, or clinical recommendations.
We identified seven obesity-related myths concerning the effects of small sustained increases in energy intake or expenditure, establishment of realistic goals for weight loss, rapid weight loss, weight-loss readiness, physical-education classes, breast-feeding, and energy expended during sexual activity. We also identified six presumptions about the purported effects of regularly eating breakfast, early childhood experiences, eating fruits and vegetables, weight cycling, snacking, and the built (i.e., human-made) environment. Finally, we identified nine evidence-supported facts that are relevant for the formulation of sound public health, policy, or clinical recommendations.
False and scientifically unsupported beliefs about obesity are pervasive in both scientific literature and the popular press. (Funded by the National Institutes of Health.)
It is curious to look at the disclosures for potential conflicts of interest in the paper - about as many as I've ever seen. And that raises yet another issue ...