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A recent study estimates that a human pregnancy demands 50,000 calories, “significantly more than the researchers expected.” The fetus only needs 4% of the energy — “the other 96% is extra fuel required by a woman’s own body.”

Discussion  5 comments

Matt G

At the same time, 180ish calories a day doesn't seem like that much to create an entire human being. That's not even a small McDonald's french fries worth of calories.

Sean K

Yes, I'm shocked that it isn't much more - but even more shocked that the researches had a number significantly below this.

Lacey V

That was my reaction too. This number is not large. The advice commonly given in pregnancy is 300 extra calories or “an extra bagel” a day, which is more than this… So the discovery seems more about the fact that most of that energy goes to the mom and not the baby, but for anyone who has actually been pregnant I feel like that’s pretty intuitive. Your body makes a lot of extra blood and gains weight that you have to move around.

Something about the math isn’t mathing for me though. If the average baby is 7 pounds, and it takes an extra 3500 calories to create a pound (of fat, anyway), then the actual baby is around 24.5k calories or half of this amount. Are they saying it’s 24.5k for baby, 50k for mom, then moms normal calories (let’s say 1800 calories/day for 40 weeks, so 504k)? In that case yeah, the baby’s weight is just about 4% of the total.

Daniel Knapp

I agree something doesn’t seem right. Also consider that the mother’s uterus and body grows to accommodate the fetus. The placenta is also sizeable.

Reply in this thread

Mike F. Edited

That 50K cal number is laughably low.
Forever, we've been told you have to run a 3500cal deficit to lose 1lb of body weight; or if you eat 3500cal surplus, you gain 1lb.
Let's go with that - probably inaccurate, but at least in the ballpark.
8lb baby = 3500 x 8 = 28000cal of energy just in "baby-matter". (Disregarding that it takes energy to synthesize said "baby-matter".)

If that's only 4% (the one number in this story that does sound about right), that'd mean that the extra energy required to make a baby is in the range of 700,000cal.
Which, over 9mos. seems way more plausible.

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