I am terrified of being pregnant. When it's even a little bit too hot out, I get so uncomfortable I just want to give up on the day. I cannot imagine what the insane physical and hormonal changes of being pregnant would do to me. I've already warned my partner that if and when I am pregnant, I'm going to be a total nightmare.
"Sorry I'm being a little rude. All my organs are being rearranged by the person I am growing inside of my body and have to carry around with me all day every day." That's going to be me. I just know it.
And it turns out, I will be totally justified in my attitude, because a new study has found that being pregnant is basically an extreme sport. It takes the same amount of endurance to bike the Tour de France as it does to gestate a human life. So when I'm pregnant, I'm going to put my feet up, and you better bring me all the chocolate and potato chips I want.
The study, which was published in the journal Science Advances, studied the metabolic rates of people participating in endurance-testing events, like the Tour de France and the Race Across the USA. Researchers studied six runners who competed in a 14-week race, where participants "run about a marathon per day six out of seven days a week," according to Quartz. That's a lot of running.
They found there is a limit to the amount of energy that human bodies can use consistently over time. It's the same limit that has been found in endurance athletes who compete in shorter competitions.
And that limit is also nearly the same as that of pregnant and lactating people.
According to Quartz, this suggests "there's a ceiling to the amount of energy humans can expend for a period of time — and pregnancy pushes these limits." I'm really going to have to send this study to my partner.
I can envision myself lying on the couch spoon-deep in a pint of Ben and Jerry's going, "I can't do the dishes right now! I'm at the limit of my endurance!" But I'd be correct! I wouldn't be exaggerating!
People who are not pregnant or extreme endurance athletes have pretty consistent metabolisms. The amount of calories we burn in a given day is fairly steady. It might fluctuate slightly with a workout here or there, but it remains pretty consistent day to day.
That completely changes in extreme athletic competitions, though. For example, someone competing in a triathlon might burn 10 times the number of calories she usually burns in a day. And if she's been pushing herself for weeks or months, running marathon after marathon or competing in a multi-day challenge, "her metabolism will still be above her baseline rate, but will gradually slow down as it adapts to the exertion."
In other words, as co-author of the study and evolutionary anthropologist Herman Pontzer says, "your body finds a way to save calories." This is exactly what happens to a person's body when it becomes pregnant.
A study from 2005 showed that pregnant people burn about twice as many calories as normal just by being pregnant.
"Humans have one of the most energy-taxing pregnancies due to a combination of the length of gestation and the size of our babies," according to Quartz. Hear that dudes? But humans are also the best endurance athletes out of all the apes. "Our species' metabolic cap could be the reason for both," Pontzer explained.
There are two possible explanations for how this came about. Our endurance capability could have evolved, giving us the side effect of allowing us to have such large babies, or the reverse could be true. We could have evolved to have large babies, which upped our endurance capabilities. According to Pontzer, "There's no reason it can't be both."
The length of pregnancies and the fact that pregnant people are trying to gain weight means pregnant people only burn twice as much energy as normal, whereas endurance athletes were found to burn 2.5 times as many calories as they normally would. Basically, being pregnant is like jogging, nonstop, for nine months. I'm already tired just thinking about it.
While the study is interesting, Quartz points out that evolution is complicated and this hypothesis may be difficult to prove definitively for several reasons. For example, pregnant people are often excluded from studies, there aren't a whole lot of extreme endurance athletes out there, and this study only had six participants.
That said, the things that happen to the human body during pregnancy are absolutely insane, and any person who does it deserves at least as many gold medals as the world's top athletes.