Researchers from US found that there was no difference between the energy expenditure of modern hunter-gatherers and Westerners which suggested that current rise in obesity is due to increased food consumption, not decreased energy expenditure.
The study measured daily energy expenditure (calories per day) among the Hadza, a population of traditional hunter-gatherers living in the open savannah of northern Tanzania.
Despite spending their days trekking long distances to forage for wild plants and game, the Hadza burned no more calories each day than adults in the US and Europe.
The similarity in daily energy expenditure across a broad range of lifestyles suggests that habitual metabolic rates are relatively constant among human populations.
The study was published in the open access journal PLoS ONE.
The research team was led by Herman Pontzer of Hunter College in New York City, along with David Raichlen of the University of Arizona and Brian M Wood of Stanford.
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The team ran several analyses accounting for the effects of body weight, body fat percentage, age, and gender. In all analyses, daily energy expenditure among the Hadza hunter-gatherers was indistinguishable from that of Westerners.
"These results highlight the complexity of energy expenditure. It's not simply a function of physical activity," said Pontzer in a statement.