![]() But it has profound implications for how we think about how deeply hardwired energy expenditure is and the extent to which we can hack it with more exercise. Or maybe the Hadza were resting more when they weren't hunting and gathering to make up for all their physical labor, which would also lower their overall energy expenditure. Maybe, Pontzer thought, the Hadza were using the same amount of energy as Westerners because their bodies were conserving energy on other tasks. (Researchers have long known this, but few had considered its significance in the context of the global obesity epidemic.)Ĭalorie burn also seems to be a trait humans have evolved over time that has little to do with lifestyle. It involved only 30 participants from one small community.īut it raised a tantalizing question: How could the hunting, foraging Hadza possibly burn the same amount of energy as indolent Westerners?Īs Pontzer pondered his findings, he began to piece together an explanation.įirst, scientists have shown that energy expenditure - or calories burned every day - includes not only movement but all the energy needed to run the thousands of functions that keep us alive. ![]() Pontzer's study was preliminary and imperfect. ![]() While the hunter-gatherers were physically active and lean, they actually burned the same amount of calories every day as the average American or European, even after the researchers controlled for body size. "We were really surprised when the energy expenditure among the Hadza was no higher than it is for people in the US and Europe," says Pontzer, who published the findings in 2012 in the journal PLOS One. When they crunched the numbers, the results were astonishing. For 11 days, they tracked the movements and energy burn of 13 men and 17 women ages 18 to 75, using a technique called doubly labeled water - the best known way to measure the carbon dioxide we expel as we burn energy. In the dry, open terrain, they found study subjects among several Hadza families. On several trips in 20, he and his colleagues headed into the middle of the savanna, packing up a Land Rover with camping supplies, computers, solar panels, liquid nitrogen to freeze urine samples, and respirometry units to measure respiration. ![]() Surely, Pontzer thought, the Hadza would be burning lots more calories on average than today's typical Westerner surely they'd show how sluggish our bodies have become. Many have argued that one of the reasons we've collectively put on so much weight over the past 50 years is that we're much less active than our ancestors. Table of contents 1) An evolutionary clue to how our bodies burn caloriesģ) Exercise alone is almost useless for weight lossĤ) Exercise accounts for a small portion of daily calorie burnĥ) It's hard to create a significant calorie deficit through exerciseĦ) Exercise can undermine weight loss in other, subtle waysħ) Exercise may cause physiological changes that help us conserve energyĨ) Energy expenditure might have an upper limitĩ) The government and the food industry are doling out unscientific adviceġ0) So what actually works for weight loss?īy studying the Hadza lifestyle, Pontzer thought he would find evidence to back the conventional wisdom about why obesity has become such a big problem worldwide. I also spoke to nine leading exercise, nutrition, and obesity researchers. To find out why, I read through more than 60 studies on exercise and weight loss. ![]() There's just one problem: This message is not only wrong, it's leading us astray in our fight against obesity. Countless gym memberships, fitness tracking devices, sports drinks, and workout videos have been sold on this promise. It's been reinforced by fitness gurus, celebrities, food and beverage companies like PepsiCo and Coca-Cola, and even public health officials, doctors, and the first lady of the United States. The spinning instructor was echoing a message we've been getting for years: As long as you get on that bike or treadmill, you can keep indulging - and still lose weight. And according to my bike, I had burned more than 700 calories. I felt like I'd worked really, really hard. "I'm going to make you work hard," a blonde and perfectly muscled fitness instructor screamed at me in a recent spinning class, "so you can have that second drink at happy hour!"Īt the end of the 45-minute workout, my body was dripping with sweat. Welcome to Show Me the Evidence, where we go beyond the frenzy of daily headlines to take a deeper look at the state of science around the most pressing health questions of the day. ![]()
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