It's no surprise that pregnancy wreaks havoc on the human body. Between the hormonal changes, physical changes, and even the changes to the brain itself, motherhood is not an alteration that should be taken lightly. The entire process of creating another human life form is designed to give the unborn fetus exactly what it needs while in utero and after birth, regardless of the negative effects it may have on the mother. In the journal Science Advances, a new study has been published linking the metabolic exertion of pregnancy to that of extreme endurance sports.
The study followed six athletic runners through a 14-week race where they were expected to run roughly one marathon per day. The study was done by scientists at Hunter College and they found that there is a maximum amount of energy that can be used before metabolic rate reaches its peak and levels off. These limits of energy expenditure are similarly shown in pregnant and lactating women. These findings showed that both pregnancy and extreme athleticism pushes these limits to the point where the body's metabolism backs off and adjusts itself accordingly.
The way metabolism works is the harder your body is pushed, the more calories you will lose. In the case of pregnancy and constant athleticism, your body begins using calories at an alarming rate. In saying that, as time progresses, your body begins to get used to the activity or energy consumption, and your metabolism levels off as it adapts.
Caitlin Thurber, who was the lead author of the published study, observed that in following the runners over the 14-week race, they were found to be using fewer calories towards the end even though they were still running the same speed and length as they were in the beginning. "We were able to show that in the face of running a marathon a day, your body finds a way to save calories," said Herman Pontzer who was a co-author on the paper.
In terms of our basic metabolism during pregnancy, we burn an extra two times the number of calories while pregnant than not pregnant. This amount is slightly less than what pro-runners burn while running daily but this could account for the fact that our bodies want to gain weight during pregnancy (not lose it).
The research team speculates that because our pregnancies require so much more energy than most other mammals (due to gestation length and offspring size), and that we are also considered one of the more abled species in terms of endurance, the fact that we have this metabolic limit where our bodies adjust to what is needed (so that we don't overuse our precious calories!), allows us to evolutionarily push our bodies further which is beneficial in both aspects of pregnancy and athletics. To read more about this interesting research, click here.