Traffic, work, kids - these are all sources of stress. And as you probably also know, stress is a drain on the body. Today on Think, Krys Boyd talked to a Harvard researcher about how our bodies respond to stress.
For our distant ancestors, stress was actually very useful.
“If a lion is chasing you – or you think a lion might chase you – it’s a good idea to get your heart rate up and run as fast as you can.," says Daniel Lieberman, the chair of the Department of Human Evolutionary Biology at Harvard. “But those kinds of stress events … tend to be short in duration but intense.”
As in you escaped the lion or you got eaten.
Either way, when we get stressed, a gland near our kidneys secretes cortisol, which provides a burst of energy.
That’s great for evading lions. But people today typically experience mental stress, rather than physical stress. That tension tends to hang around.
“The kinds of stress that we now encounter are chronic. It causes us to have high levels of blood sugar, it causes us to depress our immune systems, it causes us to sleep less, which then causes us to be stressed more.”
Essentially, we’ve figured out how to outsmart the physical dangers our prehistoric ancestors faced. But the message hasn’t made it to our bodies. For now, we just convert that excess energy to fat.
“So what’s called visceral fat, or belly fat, is actually the fat that causes most of the diseases that we care about today. Stress levels basically transfer fat to those areas. For the short term, that’s a good thing. Over long hours, years, months of stress – that’s a ruinous thing. And so many of the problems that we face today come from chronic stress.”
One more thing to stress out over.
Daniel Lieberman’s book is called The Story of the Human Body: Evolution, Health, and Disease. Think re-airs tonight at 9, or listen to the podcast.