Pregnancy Is the Ultimate Ultramarathon (and Your Metabolism Knows It)

What the book Burn teaches us about calories, survival, and why rest matters more than we think

If you’ve ever felt like pregnancy was the hardest athletic event of your life… science agrees with you.

In Burn, evolutionary anthropologist Herman Pontzer shares groundbreaking research on how human metabolism actually works—and busts some long-standing myths about calories, activity, and energy burn.

And one of his most striking claims?

Pregnancy is the ultimate ultramarathon.

Wait—How Is Pregnancy Like an Ultramarathon?

Pontzer’s research (particularly with the Hadza, a modern hunter-gatherer group) shows that our bodies are incredibly good at keeping total daily energy burn in check. We don’t burn dramatically more calories the more active we are—our bodies simply reallocate energy from other systems to make up the difference.

When you're pregnant, your body is pouring massive amounts of energy into growing a baby. That doesn’t mean your body is just “burning more.” It means your body is prioritizing differently—often pulling energy away from immune function, muscle repair, and even your brain to make it happen.

Just like an ultramarathoner in mile 47, you're adapting, conserving, surviving.

Why This Matters for Expecting and Postpartum Parents

Your fatigue isn't laziness—it's biology.
That bone-deep tiredness? It's your body reallocating energy for reproduction and survival.

You don’t need to obsess over “eating for two.”
Pontzer’s work shows our bodies are incredibly efficient—pregnancy doesn’t double your calorie needs. It tweaks how your metabolism works.

Rest is productive.
Seriously. Rest isn't optional or indulgent—it's required. Especially if you're gestating or healing from birth. Your metabolism is working hard behind the scenes.

Your metabolism doesn’t “break” after birth.
Many new parents worry about “wrecked” metabolism or “slowed burn.” But Pontzer’s data suggests that’s not the case. Your metabolism is adapting to keep you alive, not punishing you.

A New Take on Postpartum Recovery

If you’re healing from birth, feeding a baby, or just trying to remember what day it is—know this:

Your body is not broken.
Your metabolism isn’t confused.
You’re running an ultramarathon you didn’t exactly train for.
And your finish line isn’t bouncing back—it’s thriving in the long game.

Want help supporting your metabolism through real food, movement, and nervous system regulation? That’s what we’re here for.

The Beyond Birth Blueprint is built for the long game. Join the community, learn and grow and reach your goals with us!

Love,

Emily