Our sedentary lifestyles don't explain the obesity crisis.
PROBLEM: The equation is simple enough: Consume more calories than you burn off through physical activity, and you will gain weight. As such, the largely sedentary nature of the Western lifestyle is often blamed for our culture's rising levels of obesity. How legitimate is this claim, and do we desk-workers expend significantly less energy each day than do those who lead more "traditional" lifestyles?
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METHODOLOGY: The Hazda, a hunter-gatherer population in Northern Tanzania, were used as a modern manifestation of the foraging lifestyle: they procure their food without the help of modern instruments and do not consume processed foods. Using wearable GPS devices, portable respirometry systems, and urine tests, researchers tracked the Hazda's daily walking distances and measured their energy expenditure when walking and resting. This data was compared both to individuals and to populations, comprising Western, market, and farming economies.
As expected, the Hazda were, on average, much more active than members of Western society. But in a surprising twist, there was no significant
cross-cultural difference in total energy expenditure between people of similar age and body composition, at least partly because we burn more calories just sitting around than do the Hazda.