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New research says weight problems stem from our diets, not our lack of exercise.michele piacquadio/Getty Images/iStockphoto

It seems no matter where you look, someone is telling you to get more physical activity in order to lose weight and maintain health. New research suggests, however, that what we put into our mouths is even more critical than how much activity we get.

A group of researchers studied the Hazda, a tribe of about 1,500 people who still live a hunter-gatherer lifestyle in Tanzania.

The Hazda consume mainly berries and meat. The researchers thought the group would burn more calories than the average Westerner because they are more physically active.

But, surprisingly, there was no difference in the metabolic rates of men and women belonging to the tribe and those living in developed countries. In other words, we all burn similar levels of calories.

It seems to throw conventional wisdom on its head. Most of us believe that sitting behind a desk all day or watching TV for hours is the main problem when it comes to weight, while our ancient ancestors burned many more calories through physical activity.

While the Hazda are more physically active than most people in developed countries, we all burn similar levels of calories, because the Hazda expend fewer calories when they are at rest than we do.

So physical activity may not be the main factor causing many North Americans to be overweight or obese.

The main difference, the researchers found, is the Hazda consume much less food. And we simply eat too much of it.

The findings, published in the journal PLoS ONE, suggest the typical Western diet, high in processed sugar, white flour and processed food, is the key issue involved in the obesity epidemic.

That's not to say physical activity is not important. Being active has been shown to reduce risk of heart attack, stroke, diabetes and a host of other chronic diseases, while boosting life expectancy.