By Michael J. Critelli | MakeUsWell Newsletter,
We all know that much of today’s reporting—whether in mainstream outlets or alternative media—fails to meet even minimum journalistic standards. Too often, writers start with a preferred narrative and then cherry-pick or “force-fit” data to support it. Nowhere is this more pervasive than in nutrition reporting.
1. Confounding Variables and Reverse Causation
A favorite media trope is the “diet soda causes diabetes” story. One headline in Eating Well declared: “Diet Sodas May Actually Be Raising Your Diabetes Risk, New Study Says.” The fine print reveals that researchers merely found an association: participants who drank the most diet soda had a 129% higher relative risk of Type 2 diabetes than those who drank the least.
But an association is not causation. People who choose diet sodas may already be struggling with weight gain or insulin resistance—precisely the people at higher risk for diabetes. In other words, drinking diet soda may be an effect, not a cause, of underlying problems.
Even when studies attempt to control for confounding variables (age, gender, existing health status, income, exercise), unmeasured differences remain. Observational studies can suggest relationships, but they rarely prove anything.