Cause and Effect

The Academy of Nutrition and Dietetics releases a daily Nutrition and Dietetics SmartBrief, which contains summaries of and links to recently released health and nutrition articles. Earlier this month, a headline in a recent issue read, “Too much sitting increases risk of early death, study says.”

The problem is that no, that is not what the study says. In fact, the HealthDay article that the SmartBrief links to states, “The study couldn’t prove cause and effect . . .” and a couple of paragraphs later, the article continues, “It’s not clear why prolonged sitting is unhealthy, Patel [lead researcher, Dr. Alpa Patel] said. It’s possible that people who spend a lot of time on the couch also have other unhealthy behaviors, such as excess snacking, she suggested.”

Okay, let’s back up a moment. First, the author who wrote the SmartBrief’s headline misrepresented the study’s findings by implying causation, and second, Dr. Patel herself seemed to disregard the limitations of her own research by labeling sitting as “unhealthy” based on an association.

This was not just a SmartBrief problem. Other news outlets picked up the story and similarly misled consumers. For example, the headline on NBC News read, “Here’s more evidence sitting too much can kill you,” with the subheading, “Sitting more than six hour [sic] a day during your free time raises the risk of early death by 19 percent.” No, that is not what the research found at all, but such sensationalism probably draws more clicks than a mundane – but more accurate – headline.

We see similarly misleading language when it comes to reporting on the research that investigates the relationship between weight and health. Headlines summarizing these pieces oftentimes imply a causal relationship between increased body weight and morbidity. Remember, however, that when researchers set out to investigate the consequences of obesity, they are also studying the impacts of weight stigma, dieting, weight cycling, socioeconomic disparity, healthcare discrepancies, and everything else that tends to come packaged with the experience of having a bigger body in today’s world.

While increased adipose tissue in and of itself could be a causal factor for certain health conditions, similar to how having fair skin increases one’s skin cancer risk, establishing a causal relationship is extremely difficult given the confounding variables. To assume causation because of correlation is premature at best, and at worst, it could be completely wrong.

Next time you see a headline that implies causation, remember that said headline might be more sensational than factual, as the actual research behind it is probably more complex and nuanced than can be accurately distilled into a single line of text or a sound bite.