Health Claims Warning: Beware of ‘The Cockroach Effect’!

In my 25 or so years in the health field, I have witnessed the comings and goings of a multitude of highly acclaimed scientific findings. Over and over again, a new piece of data, often something related to the risk of death or disease, will appear in scientific literature and instantaneously saturate the global media. And over and over again, often not long after the initial announcement, comes another study or numerous studies convincingly refuting the original findings. Somehow, however, these new studies rarely garner even a fraction of the attention paid to the original, whose conclusions continue to be presented as indisputable fact.

Those of us who have been involved with the Health At Every Size® model over the years are all too familiar with this phenomenon. Remember the “300,000 people killed by obesity” statistic that first surfaced in the prestigious (but not infallible) “New England Journal of Medicine” (NEJM) in 1996?  The claim was dredged up incorrectly from a study published a few years earlier in the “Journal of The American Medical Association” (JAMA). In fact, the authors of this JAMA article published a response to the NEJM article protesting the bogus claim. In addition, the 300,000 number was formally debunked in 2005 by epidemiologists from the Centers for Disease Control and Prevention (CDC). Yet to this day, almost a decade later, this bogus, fear-laden statistic is commonly bandied about (and rarely challenged) in the media and at health-related conferences.

And who can forget the “our children will be the first generation not to live as long as their parents because of obesity claim made by Olshansky and colleagues again in the NEJM in 2005. Confronted about the origins and accuracy of their frightening claim just a few months later in an exposé in “Scientific American,” the authors responded with:

“These are just back of the envelope plausible scenarios. We never meant for them to be portrayed as precise.”

In spite of this and even though the World Health Organization and the U.S. Social Security Administration have projected that life expectancy will continue to rise in the foreseeable future, this scary piece of non-science is commonly repeated today by health professionals and the lay public as if it were an “evidence-based” fact of life.

I call this unfortunate and all too common phenomenon “The Cockroach Effect.” Cockroaches are amazingly resilient little creatures. They can continue to be active after not eating for 30 days. They can survive without air for 45 minutes and have been known to recover after being under water for 30 minutes! If you have ever tried to kill a cockroach or get rid of an infestation, you know it is no easy task.

Neither is trying to erase attention-grabbing but faulty health-related claims once they have appeared.

“The Cockroach Effect” is certainly not limited to weight-related research. Dr. John Ioannidis has spent his career challenging his peers by exposing the personal biases, economic pressures and downright bad science that plague the medical profession. In a seminal paper in PLOS Medicine online in 2005, he presented a model that predicted correctly that 80% of non-randomized studies, 25% of randomized trials and 10% of large randomized trials were typically refuted by later research. Although we expect contradictions as part of science, Ioannidis also found that even when faulty research was debunked, its conclusions typically persisted for years or even decades. The details of his fascinating findings are explored in an article entitled “Lies, Damned Lies and Medical Science,” which appeared in the “Atlantic Magazine” in November 2010.

Sometimes the lingering of these faulty claims is fairly benign. It probably doesn’t hurt to drink eight glasses of water a day; even though the scientific basis of this recommendation is elusive at best (I am guessing it may have originated with the promotion of drinking more water as a weight-loss technique). Sometimes, after enough years have passed and sufficient conflicting evidence has accumulated, the faulty claims actually get laid to rest. This may finally have happened with the “if you don’t exercise for at least 30 minutes, it won’t do you any good” mantra.

But when it comes to issues like weight and health, where there is so much deeply rooted socio-cultural and economic investment in the status quo, it can be quite a different story. We see all too clearly the heartbreaking consequences in the billions of dollars spent on fruitless and sometimes dangerous weight-loss schemes and scams and the lives torn apart by disordered eating and weight stigma. My recommendation is that when reading health-related claims in the literature, we stay vigilant and be on the lookout for “The Cockroach Effect” – faulty data that will not die!


Jon Robison, PhD, MS, MAJon is an accomplished speaker, teacher, writer and consultant. He has spent his career advocating that health promotion shift away from its traditional, biomedical, control-oriented focus, with a particular interest in why people do what they do and don’t do what they don’t do. Jon has authored numerous articles and book chapters and is a frequent presenter at national and international conferences. He is also co-author of the book, “The Spirit & Science of Holistic Health — More than Broccoli, Jogging and Bottled Water, More than Yoga, Herbs and Meditation.” This work formed the foundation for one of the first truly holistic employee wellness programs — Kailo. Kailo won awards in both Canada and The United States, and the creators lovingly claim Jon as its father. Contact Jon at: or

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