The Real Cause of High Cortisol in Female Runners

Why Underfueling Raises Cortisol in Female Runners

Last week, an incredible woman who is starting to train for her first marathon shouted me out on Instagram after joining Run Fuel, and my inbox was flooded with responses to my new follower welcome message.

I’m not joking when I say nearly half of these messages said something like this:

A screenshot of a message from a woman asking if she should stop running after menopause because she's been told running raises cortisol and isn't good for her body. — Screenshot

Multiple women told me they stopped running, but are afraid to come back to it in their 40s and 50s, even though they loved it.

It makes me sad.

Let’s make something clear:

Does Running Really Raise Cortisol?

Yes, running raises cortisol… temporarily. And it’s a natural, healthy response that will NOT magically trigger belly fat, even if you’re in perimenopause.

Acute vs. Chronic Cortisol

What does cause fat storage is chronically elevated cortisol levels — which is different from the acute cortisol spike you get post-run.

Let’s look at two female runners. One who may have elevated cortisol, and one who likely doesn’t.

Runner A: When Stress Starts to Add Up

Runner A, age 45.

Training for her 3rd half marathon, runs 25 miles/week.
Runs with a friend who’s slightly faster than her 2 days a week, but she can keep up.
She doesn’t eat anything before weekday runs because she’s not hungry, and drinks a protein shake on the way to work afterward. She has a Trader Joe’s salad and apple for lunch.
Her co-worker recently quit and she’s handling 2 jobs at work. Her teenage daughter is dealing with bullies at school.
She often works after the kids go to bed and then watches Netflix with her husband because it’s their only time together.
She often wakes up at 3 AM with her to-do list on her mind and feels hungry but tries to ignore it.
She tries to run her long runs as close to her goal race pace as possible. She takes one gel with her but sometimes forgets to take it. She spends most of Saturday at her son’s baseball games, running errands, and finds herself starving at 4 PM and pulling into Chick-Fil-A.

Runner B: Supporting Recovery and Performance

Runner B, age 45.

Training for her 10th marathon, running 6 days per week.
Does 1 speed workout and 1 tempo run per week, and runs 2-3 min/mile slower than marathon pace on recovery days.
She eats a piece of toast and banana before weekday runs and a whole bagel with honey, banana, and juice before long runs. She has 2 cups of coffee before noon and a grain bowl for lunch.
Her co-worker recently quit and she’s handling 2 jobs at work too. Her teenage daughter is also dealing with bullies at school.
She journals each morning when she wakes up and stops looking at Instagram at 8 PM and reads before bed.
She runs her long runs at a conversational pace with friends and takes 2-3 gels per hour. She spends most of Saturday at her son’s baseball games and running errands, but always eats a big breakfast right after her run and has leftovers in the fridge for a late lunch.

Why Runner A Has Higher Cortisol

Runner A probably has higher cortisol levels, her running is plateauing and feels like she is gaining weight despite working hard.

Here’s why:

Cortisol elevates when training load is consistently too high without adequate recovery. Runner A and B both spike their cortisol when they run — but Runner A contributes to chronic stress on EVERY run, because she never runs any runs easy — they’re all hard or very hard (yes, even though she can talk to her friend). Runner A also doesn’t get as much sleep as Runner B. Even though she’s not running as many miles, she’s not recovering as quickly.
Cortisol elevates when stress is not managed. Runner A and B both have life stress — both at work and within their families. Runner B uses journaling, technology boundaries, and reading to manage her stress. Runner A ignores her stress.
Cortisol elevates when runners under fuel. Runner A and B both run enough to create a significant glycogen depletion. Runner A is chronically under fueling. Not only is she not eating enough before her runs, but she’s not eating enough carbs all day. Her body slows down fat burning to preserve energy. Runner B’s glycogen is depleted during her hard workouts, but she refuels them. Her body isn’t worried about when it’ll get more carbs.

What Really Causes High Cortisol in Female Runners?

So no. Running alone doesn’t cause chronic cortisol levels.

Under fueling, stress, and improper training load does.

Is there a scenario where it makes sense NOT to train for a half marathon or marathon? Yes – for a runner going through a period of extreme stress, it can make sense to put the long distance racing goals on a temporary pause because to the body – all stress (whether it’s a 20 mile long run or an email from your lawyer) is stress. And if the body is handling too much stress it will do what it can to slow you down.

Female Runners Can Thrive After 40

But, for the majority of female runners navigating normal life stress, if you train and fuel well, you can love your body and feel amazing during training — even over 40.

Happy running,

Nicole Dobransky