There's a new study on obesity that caught our eye this morning. It makes the bold claim that modern day hunter-gatherers in East Africa burn as many calories a day as sedentary office workers here in America. The study compared populations and found that both groups tend to use the same amount of energy, suggesting that America's obesity has more to do with what we eat — not how much we sit.
If you are having trouble swallowing that conclusion — we did too.
Herman Pontzer is the the lead author of the study, and says that through evolution, our metabolism adapt to our environments. So, the hunter-gatherers they studied are burning their calories through physical activity, walking miles a day, we're burning the same amount of calories another way — ways you can't see.
"The first thing to understand is that physical activity is only a small part of your total energy expenditure every day. It's only the tip of the iceberg. Most of the energy you spend every day is spent on things happening at the cell level. So your immune system, and your reproductive system, your digestive system and heart and brain are burning calories all day. That activity that happens under the surface is the majority of your energy expenditure every day," Pontzer said.
Pontzer says our bodies find a balance with whatever our level of acvity is. your metabolism adjusts. He says the reason for this is that throughout human history, we've had to adjust to different amounts of food — sometimes there's a good harvest, sometimes the crops all die. So our bodies have to be flexible in terms of how much energy they expend.
Pam Emernon, a coach at Cross Fit 626, says that bodies adjust to whatever exercise routines people have. So if you run for an hour a day, it may be hard at first and you'll burn a lot of calories, but soon it will seem easy.
"If you do the same thing over and over, your body does adapt to it. Same with diet, that is why people cycle through different foods, so your body doesn't adapt to the same thing you are doing, whether it is diet or exercise," Emernon said. She said the only way to stop your body from doing this is to contantly vary your exercise routines.