Be Cause: The Mighty Struggle to Discern Causality

What is going on here? Why is this happening? What is the cause? The struggle to discern causality bedevils anyone who is serious about understanding obesity and how to overcome it. But the line between cause and effect can be very blurry, and fuzzy thinking ensues. And thus, the progress toward reversing the relentless increase in obesity is so disappointing. Assumptions about causality repeatedly foil our efforts in this struggle.

Is too much fat in our diets the problem? Decades of promoting low-fat diets had little effect for reducing obesity. Maybe too much sugar is the problem? Two decades of reduction in sugar consumption did not change the upward trend of obesity.

In so many dimensions of this problem, discerning causality is a struggle.

Keeping the Record Straight

So it is that we have come to appreciate disciplined efforts to maintain the bright line that separates correlation from causality. For example, we see a study to evaluate the effects of an obesity prevention program in South African schools. The publication characterized the study design as a cluster randomization and their findings as evidence of effectiveness.

But a closer look revealed that the assignment of study groups wasn’t random. The research team instead chose which schools to assign to which groups. They had their reasons. But this meant that the study was not a randomized experiment. It was a quasi-experimental design. And thus, the findings were an association with the intervention. Not evidence for causality.

Through collegial dialogue, the investigators reached a shared understanding with experts from the IU School of Public Health and jointly issued an correction this week to ensure integrity for the scientific record.

Distinguishing Presumptions from Evidence of Causality

This is but one example to illustrate the challenge of distinguishing presumptions about causality from clear evidence in the realm of obesity science. Such examples are easy to find. The problem arises in policy to address obesity when advocates express certainty that their favorite policy will reduce the problem. Likewise, it arises when people use a modeling study to hype the problem by constructing a scary death toll.

The fact is that hyperbole and presumptions about what will work in addressing obesity merely get in the way of finding real solutions. Hyperbole sparks resistance. Presumptions lead us astray. Thus we must focus on what we really know about the problem, its causes, its effects, and the effects of interventions to reduce it.

Discerning causality helps with all of this.

Click here for further perspective on the importance of discerning causality to guide obesity policies.

Mystery and Melancholy of a Street, painting by Giorgio de Chirico / WikiArt

Subscribe by email to follow the accumulating evidence and observations that shape our view of health, obesity, and policy.

May 13, 2022