Rising Obesity: The Third Half of the Root Cause

Colour CircleFor a very long time, a basic question about the rising rate of obesity has seemed to frustrate people. Why is it relentlessly rising? Some pundits seem to think people have become stupid, lazy, or undisciplined over the last several decades. “You think cake wasn’t delicious iu 1969?” quipped one self-appointed expert recently. Others are certain that the problem lies in changes to the food supply or the physical environment or pollution or stress and distress. But the unsatisfying truth is that rising obesity is likely not traceable to a single root cause.

But a few things are clear.

It’s the Environment, Stupid

A recent paper in Public Health attempts to model the factors that might explain the cause of rising obesity in Brazil. Samuel Dumith and colleagues undertook an ecological analysis of behavioral and contextual factors. It was a time-series study of the period from 2006 to 2020. They constructed a model that explained 81 percent of the growth in obesity over the last 15 years.

Their conclusion was quite straightforward. The factors that do the best to explain rising obesity in Brazil are all about environmental context. Changes in our circumstances correlate better with the rising pattern of obesity than health-related behaviors do. Among such behaviors, the best predictor was physical activity. But other than that, social and economic factors were best for explaining the growth of obesity in Brazil. These are things like urbanization, GDP per capita, education, and income.

Ineffective Policies Focused on Promoting Better Behaviors

The authors make special note of the importance of focusing on how our social and economic environment may promote obesity:

“In Brazil, although there is no exclusive policy to combat obesity, the theme is recurring within policies that mainly focus on promoting adequate nutrition and encouraging the adoption of healthy lifestyle behaviours. To date, these policies do not appear, by themselves, to have had significant impacts on curbing the increase in obesity in the country. This can be explained, in part, by the results of the present study, which demonstrate that contextual factors appear to contribute hugely to the increased prevalence of obesity.”

Contributing Factors Sum to More Than 100 Percent

This brings us to the old problem of nature versus nurture. It’s a silly argument to have because when we do, we are falling into an atomistic fallacy. We presume that the influence of genes and environment must sum to 100 percent in their power to explain obesity.

But in fact, they act in concert. Our genes set the table for obesity. It is a highly heritable condition. And then the environment serves it up.

Behavioral strategies may be helpful for coping with obesity on an individual level. For preventing it in the population, though, they have not proved to be very effective.

Click here for the Dumith paper and here for perspective on why environmental and genetic influences for obesity sum to more than 100 percent.

Colour Circle, painting by August Macke / WikiArt

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


August 17, 2022