Hunter-gatherers expend same calories as average Americans

Taking in too many calories far outweighs getting too little exercise as a cause of obesity, according to a study of a hunter-gatherer society co- authored by Yale anthropologist Brian Wood and recently published in the July issue of the journal PLoS One.

Using state-of-the-art technology to measure the daily energetic expenditure of the Hazda, a foraging people of Tanzania, Wood and co-authors Herman Pontzer (Hunter College) and David Raichlen (University of Arizona) discovered that even though these last remaining hunter-gatherers in Africa are quite physically active, they expend on average no more calories in a day than the adult population of the industrialized world. Given the total lack of obesity among the Hadza, whose average daily calorie consumption is far lower than that found in the developed world, the researchers concluded that increased caloric intake is the main source of rising obesity in Western populations.

While activities such as digging for tubers keep the Hadza people active, researchers have found that, overall, they expend about as many calories each day as average Americans.

The finding that energetic expenditure is more similar across a broad range of cultures than previously assumed challenges the widely held belief that a recent shift to a more sedentary lifestyle is largely responsible for the worldwide obesity pandemic, note the researchers. “This was one of those ‘a-ha’ moments in evolutionary science, when testing our assumptions about other cultures teaches us something about ourselves,” Wood says

The counter-intuitive finding has huge evolutionary implications, contends Wood, who says that our evolved preference for energy-dense foods poses risks as such foods become increasingly easy to acquire. “Ultra-convenient, modern food markets are novel in an evolutionary sense, and today we might get pleasure from a diet that over-supplies us with calories,” he notes.

He cautions that these findings are not to be read as reason to abandon physical exercise. “Numerous studies demonstrate that physical exercise is beneficial in many ways to human health,” he notes. “While our study would certainly recommend increased focus on one’s food intake, it in no way supports canceling your gym membership.”

Other authors of the study are Audax Z. P. Mabulla, Susan B. Racette, and Frank W. Marlowe.

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4 thoughts on “Hunter-gatherers expend same calories as average Americans”

  1. But, Puma BearClan, this study measured physical activity and found that the Hadza do indeed do much more than we do in the West – what’s interesting is that they don’t burn up any more calories whilst they’re doing it! In other words, if they ate much more of the food they already eat, they would most likely gain weight! It’s their low calorie intake which is keeping them thin – not the kind of food they eat or the physical activity they do.

    • I do see your point. It would be interesting to know the macronutrient breakdown of their diet. My personal experience with very low carb / ketogenic diets (less than 100 calories to less than 50 calories of carbohydrates daily) and also the information that others report is that the caloric intake can be rather high (2500-3000 calories per day, mostly from animal fat) and yet weight will be lost or maintained due to a metabolic adjustment. I notice that the image is of the Hazda digging for tubers… Starches are usually low-nutrient and calorie-dense and are not a typical part of a very low carb or ketogenic diet. So perhaps the notion that the VLC or ketogenic diet is that of “hunter-gatherers” is not universally correct; the native diets that are most often described by the VLC oeuvre are maritime and subarctic. It would also be interesting to know how authentic the Hazda lifestyle is with climate change over the past several hundred years and perhaps diminishing hunting opportunities, which seems to be a problem for nearly all traditional hunting peoples across the world.

      • I have read the article “Debunking the Hunter Gatherer Workout” in the New York Times by Herman Pontzer, who cofounded the Hazda Fund. The Hazda Fund mission statement is to: “…support healthcare and research initiatives that improve the health of the Hadza people and promote a better understanding of their culture.” (From their website.) The authors of this study, then, seem to be deeply involved in affecting the Hazda. The website also states that “Climate change and population growth also threaten Hadza access to the wild game, wild plants, and water on which they depend. Much of their traditional homeland has already been lost to them.”

        I’m dismayed that the articles that appear in our media describe what appears to be unbiased research but is in fact the description of a population under stress, and heavily influenced (if not “managed”) by interference from outside. After reading about the Hazda and their struggles, I think it is a shame that this article and similar ones are being published without full disclosure. Comparing a struggling subsistence population with one of the “first world” is a disservice to both, and further claims that the Hazda are representative of the hunter-gatherer is a sham, in my opinion.

  2. Really? After so many years of research on the quality of metabolic function determined by the type of calories consumed, we still have these “calories in equals calories out” studies, articles, and repetition. In the past five years of research and personal experience in paeolithic and low-carb diets I have yet to come across the argument that this researcher disputes: that the hunter-gatherer lifestyle is more active, thus explaining the lack obesity.

    The basic premise of embracing the paleolithic, hunter-gatherer, low-carb diet is that the calories of animal protein and animal fat are metabolized differently than plant materials and the predominantly carbohydrate-based diet of the “west.”

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