Scores of Americans increase exercise in the fight to lose weight. Yet, scientists say sedentary behavior isn’t the primary cause of the American obesity epidemic. For that, look to the scourge of the modern supermarket — processed foods.

Indeed, scientists say Americans actually burn more calories than people in developing countries living traditional lifestyles.

A study by scientists at Duke University analyzed data from 34 different populations around the world, totaling more than 4,000 people. These included everyone from Norwegian office workers to Tanzanian hunter-gatherers.

Participants’ physical activity was tracked, and the data offered some surprising findings.

Scientists saw that energy expenditure in developed countries is higher than in developing nations, which was unexpected. Sedentary behavior is often associated with wealthier nations. This finding contradicts the idea that less physical activity is linked to obesity.

In the 25 nations where dietary data is available, the study found that those who ate ultraprocessed foods were, on average, heavier.

These foods include packaged cookies or cakes, ice cream with preservatives, processed meats like hot dogs or luncheon meats, and sugary drinks.

This finding, by itself, isn’t surprising. But it is when coupled with the increased energy consumption in nations where obesity is more prevalent.

None of this suggests you shouldn’t exercise anyway. Doing so prevents heart disease, improves mental health and extends life. And burning calories on a treadmill or bicycle still helps you lose weight … although perhaps not as much as any of us would like.