Inactivity or overeating? For the young, which is the bigger obesity villain? This question, in the words of journalist Gretchen Reynolds,
[…] remains murky and matters, as obesity researchers point out, because we cannot effectively respond to a health crisis unless we know its causes.
People are still talking about the research on…
[…] the lifestyles, diets and body compositions of Amazonian children who live in rural, foraging communities… The in-depth study found that the rural children, who run, play and forage for hours, are leaner and more active than their urban counterparts. But they do not burn more calories day-to-day, a surprising finding that implicates the urban children’s modernized diets in their weight gain.
The Shuar are pretty much hunter-gatherers, with some fishing and subsistence farming added to the mix. Of necessity, their diet includes starchy vegetables, which are not favored by nutritionists. And yet, it is rare for either children or adults to be overweight or to suffer from malnourishment.
The Ecuadorian kids are not the only ones concerned, since the facts are believed to “have implications for the rising rates of obesity in both children and adults worldwide.”
In a previous study, Dr. Sam Urlacher compared the Shuar children’s energy expenditure with that of some sedentary, heavy children in the USA. Turns out, the young Ecuadorians burned pretty much the same number of calories as the overweight North Americans. In the followup study, those rural Shuar children were compared to some Shuar townies, in the same age group and with the same genetic heritage.
The urban Shuar children proved to be considerably heavier than their rural counterparts. About a third were overweight by World Health Organization criteria. None of the rural children were. The urban kids also generally were more sedentary. But all of the children, rural or urban, active or not, burned about the same number of calories every day.
Study co-author Dr. Herman Pontzer of Duke University teaches evolutionary anthropology, with an emphasis on the intersection of evolution and human metabolism. Apparently, the influence goes both ways. Dr. Pontzer had also previously studied the Hadza, hunter-gatherers of Tanzania, who spent their days in moderate-to-strenuous activity while burning “about the same number of total calories daily as much-more-sedentary Westerners.” His thought is that our bodies figure out where to allocate the available energy, according to whatever we are doing with our lives. Reynolds says,
The result is that our average, daily energy expenditure remains within a narrow band of total calories, helpful for avoiding starvation among active hunter-gatherers, but disheartening for those of us in the modern world who find that more exercise does not equate to much, if any, weight loss.
She goes on to quote Dr. Urlacher:
Exercise is still very important for children, for all sorts of reasons. But keeping physical activity up may not be enough to deal with childhood obesity.
Your responses and feedback are welcome!
Source: “Exercise vs. Diet? What Children of the Amazon Can Teach Us About Weight Gain,” NYTimes.com, 02/24/21
Image by Maurizio Costanzo/CC BY 2.0