Food may contribute more to obesity than exercise

While diet and exercise have long been known as the two main pillars of health, it turns out diet may be doing more of the heavy lifting than previously suspected. New research shows that the difference in global obesity levels could be tied more to the consumption of ultra-processed foods than to a sedentary lifestyle. More focus must therefore be put on improving food quality to help fight obesity.

The diet demise

The food we eat "plays a far greater role than reduced energy expenditure in obesity," said a study published in the journal PNAS. After collecting data for 4,213 men and women from 34 countries or cultural groups, researchers found that the "total calories burned per day is really similar across these populations, even though the lifestyle and the activity levels are really different," said Herman Pontzer, a professor of evolutionary biology and global health at Duke University and senior author of the study, to NPR.

The study's findings support a theory about human metabolism called the constrained total energy expenditure model, which says that "our brains and bodies closely monitor our total energy expenditure, keeping it within a narrow range," said The Washington Post. Essentially, the body's metabolism adjusts to a person's lifestyle. For example, "if we start consistently burning extra calories by, for instance, stalking prey on foot for days or training for a marathon, our brains slow down or shut off some tangential biological operations, often related to growth, and our overall daily calorie burn stays within a consistent band."

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This means there has to be a culprit other than exercise contributing to the obesity levels in many developed countries. And all signs point to our diet, namely the consumption of ultra-processed foods. A subanalysis by the researchers "found that people in countries that got more of their calories from ultra-processed foods tended to have more obesity and higher body fat percentages," said NPR. These foods are "making us fat not just by tempting us to eat more, but also by allowing our bodies to absorb more calories from each bite," said News Medical.

Fixing the food

While there seems to be a connection between ultra-processed foods and obesity, this study does not establish causality as there was a lack of "detailed dietary data for most of the populations in this dataset," said the study. There are also likely other "environmental, societal and physiological factors promoting increased caloric intake and absorption" that have not yet been resolved. However, the data does suggest that caloric intake contributes approximately 10 times more to obesity than reduced energy expenditure.

These findings could change the way we look at obesity as a health problem. "For decades we've been telling Americans that you're lazy, it's your fault, you're not moving enough, you're eating too much," said Dariush Mozaffarian, the director of the Food is Medicine Institute at Tufts University, to NPR. "And I think what this study shows is that there's really complicated biology happening and that our food is driving this." Many Americans do not have access to healthy, high-quality food, which increases their risk of obesity.

Despite the study findings, exercise is still extremely important for health. "Diet and physical activity should be viewed as essential and complementary, rather than interchangeable," said the study. But a focus could be made on improving the quality of available food and reducing the reliance on ultra-processed foods. "We can't outrun a bad diet," said NPR.