Why I Broke Up with Fasting in my 40's !!!!

Hey everyone, Kate here.

If you’ve followed me for a while, you know I used to be an advocate for intermittent fasting. In my 30s, it felt like a superpower-clear head, steady energy, and a "reset" button for my metabolism. But once I hit my mid 40's and entered the wild world of perimenopause, that superpower has started feeling more like a kryptonite.

Lately, if I skip breakfast, I’m not "focused"—I’m irritable. I’m not "burning fat"—I’m exhausted and reaching for the nearest snack by 2:00 PM. I started wondering: Is it me, or is the fasting just not working anymore? 

The "Stress" Connection

It turns out, my gut feeling was right. In perimenopause, our hormones—estrogen and progesterone—are already on a rollercoaster. Adding the stress of a long fast can sometimes push our bodies over the edge.

According to Dr. Stacy Sims, a leading exercise physiologist and nutrition scientist specializing in female physiology, women in perimenopause and menopause are more sensitive to the stress of fasting than men or younger women (Sims, 2024). When we fast, our bodies perceive a "low energy state," which can spike cortisol (our stress hormone).

High cortisol during perimenopause is a double-edged sword:

• It can lead to muscle loss (the opposite of what we want!).
• It can disrupt our thyroid function, which is already under pressure.
• It can contribute to that stubborn "mid-section weight gain" we’re all trying to avoid (Sims, 2024).

Listening to the Body Over the Clock

When your hormones are shifting, your mood and energy are already fragile. Dr. Sims notes that for active women especially, fasting can keep cortisol elevated, leading to higher anxiety and disrupted sleep (Sims, 2024).

I’ve realized that my body doesn't need another stressor right now. It needs stability.

Instead of watching the clock to see when I'm "allowed" to eat, I'm focusing on:

1. Protein-First Mornings: Prioritizing 30-40g of protein within an hour of waking up to stabilize my blood sugar.
2. Circadian Eating: Eating when the sun is up and stopping a few hours before bed, rather than doing extreme 18-hour fasts.
3. Grace: Acknowledging that what worked at 25 doesn't have to work at 45.

If you’re over 45 and feeling like fasting is making you "hangry" or depleted, you aren't failing the "diet." Your body might just be asking for more fuel to navigate this hormonal transition.

The rules change after 40 — especially around food and hormones. Kate's Real Food Guide is built on exactly this reality: no fasting, no restriction cycles, just high-protein whole-food eating that actually works for the female body after 40.

Get Kate's Real Food Guide — $29.99 →

References

Sims, S. (2024, July 23). Dr. Stacy Sims: Female-Specific Exercise & Nutrition For Health, Performance & Longevity. Huberman Lab - Podcast Notes. https://podcastnotes.org/huberman-lab/dr-stacy-sims-female-specific-exercise-nutrition-for-health-performance-longevity-huberman-lab/

Sims, S. (2024, October 10). Intermittent Fasting & Female Athletes. Dr. Stacy Sims. https://www.drstacysims.com/newsletters/articles/posts/You_are_an_athlete_and_you_shouldnt_practice_intermittent_fasting