If you have ever walked into a room and forgotten why you were there, lost your train of thought mid-sentence, or struggled to find a word that was "right on the tip of your tongue," you are not alone. Brain fog is one of the most frustrating and frightening symptoms of perimenopause, affecting up to two-thirds of women during this transition.
Many women worry they are developing dementia or losing their minds. The good news is that science has uncovered a remarkable cellular process that may help clear the fog—and it does not require expensive supplements or medications.
What Is Autophagy?
The word "autophagy" comes from the Greek words meaning "self-eating," which sounds alarming but is actually one of the most beneficial processes in your body. Autophagy is your cells' natural cleaning and recycling system. When activated, your cells identify damaged proteins, dysfunctional components, and accumulated debris, then break them down and recycle the raw materials to build new, healthy cellular parts.
Think of it like a deep spring clean for every cell in your body. Over time, cellular "rubbish" accumulates—damaged proteins, worn-out mitochondria (your cells' energy factories), and other debris. Without regular cleaning, this buildup impairs how well your cells function. In the brain, this accumulation has been linked to cognitive decline, memory problems, and even neurodegenerative diseases like Alzheimer's.
The discovery of autophagy was so significant that Japanese scientist Yoshinori Ohsumi was awarded the 2016 Nobel Prize in Medicine for his research into its mechanisms.
Why Autophagy Matters During Perimenopause
During perimenopause, your brain is under significant stress. Fluctuating oestrogen levels affect neurotransmitter production, sleep quality deteriorates, and many women experience increased inflammation throughout their bodies. All of these factors can contribute to the accumulation of cellular debris in the brain.
Research has shown that autophagy activity naturally declines with age. This means that just when your brain needs more cleaning support, your cellular maintenance system is slowing down. A groundbreaking 2019 study published in Current Biology demonstrated that reduced autophagy in the hippocampus (the brain's memory centre) correlates with age-related memory decline—and crucially, that restoring autophagy levels was sufficient to reverse these memory deficits.
This finding offers genuine hope: the brain fog you are experiencing may not be permanent or progressive. It may be, at least in part, a consequence of reduced cellular maintenance that can be addressed through lifestyle changes.
How Fasting Activates Autophagy
The most powerful natural trigger for autophagy is fasting. When you stop eating for an extended period, your body shifts from "growth mode" to "repair mode." Without a constant supply of nutrients, your cells begin recycling their existing components to maintain function. This is when autophagy ramps up significantly.
Research indicates that autophagy begins to increase after approximately 12 to 16 hours of fasting, with more significant activation occurring between 24 and 48 hours. However, you do not need to undertake extreme fasts to benefit. Even the popular 16:8 intermittent fasting protocol—eating within an 8-hour window and fasting for 16 hours—can provide meaningful autophagy activation.
| Fasting Duration | What Happens |
|---|---|
| 12 hours | Autophagy begins to increase; body starts shifting to fat-burning |
| 16 hours | Significant autophagy activation; cellular cleaning accelerates |
| 24 hours | Enhanced autophagy; deeper cellular repair processes engage |
| 48+ hours | Maximum autophagy (requires medical supervision) |
The BDNF Bonus
Fasting does more than just activate autophagy. It also increases production of Brain-Derived Neurotrophic Factor (BDNF), a protein that supports the survival and growth of neurons. BDNF is essential for memory, learning, and higher cognitive functions—exactly the areas affected by perimenopause brain fog.
Interestingly, BDNF also supports nitric oxide production—another crucial molecule that declines during perimenopause. Learn more about this connection in our article on The Nitric Oxide Connection: Why This Molecule Holds the Key to Perimenopause Energy.
Healthy levels of BDNF support the hippocampus and prefrontal cortex, the brain regions most vital for clear thinking and memory formation. Even better, BDNF itself stimulates autophagy, creating a virtuous cycle: fasting increases BDNF, which enhances autophagy, which clears cellular debris, which improves brain function.
A Gentle Approach to Intermittent Fasting
If you are new to fasting, the key is to start gently. Your body needs time to adapt, and pushing too hard too fast can backfire—especially during perimenopause when your system is already under stress.
Your 4-Week Fasting Introduction
Week 1: Awareness
Simply notice your current eating patterns. What time do you typically have your first meal? Your last?
Week 2: Extend the Overnight Fast
Try pushing your breakfast back by one hour. If you normally eat at 7am, wait until 8am.
Week 3: Move to 14 Hours
Continue pushing breakfast later, aiming for a 14-hour fasting window.
Week 4: Reach 16 Hours
If comfortable, extend to a 16-hour fast. This is the classic 16:8 protocol.
Important: During your eating window, focus on nutrient-dense foods. Perimenopause is not the time for calorie restriction—your body needs adequate nutrition. The goal is when you eat, not how much you eat.
What Works for Me
I've been doing this for many weeks now, and I've found a rhythm that works for my life. I eat my last meal between 6 and 7pm—and I try not to binge on things during my eating window, though sometimes... well, we're all human!
General advice is not to eat too much before bed. I actually retire around 9pm because I'm an early riser, but this seems to work well for me. Then I try not to eat before 12 noon at least twice a week. On other days, I get as close to that time as I can—but this is just a rule of thumb, not a strict prerequisite.
It becomes quite normal after a short time, and it helps me with weight control too. The key is finding what fits your life—not following someone else's schedule rigidly.
Foods That Support Autophagy
While fasting is the most powerful autophagy trigger, certain foods and compounds can support the process when you are eating:
| Food/Compound | Source | How It Helps |
|---|---|---|
| Resveratrol | Red grapes, berries, red wine | Activates autophagy-related proteins |
| Curcumin | Turmeric | Enhances autophagy and reduces inflammation |
| EGCG | Green tea | Stimulates autophagy pathways |
| Omega-3 fatty acids | Fatty fish, flaxseeds, walnuts | Supports brain autophagy specifically |
| Spermidine | Aged cheese, mushrooms, legumes | Directly induces autophagy |
When NOT to Fast
Intermittent fasting is not appropriate for everyone. You should consult your healthcare provider before trying fasting if you:
- Have diabetes or blood sugar regulation issues
- Are pregnant or breastfeeding
- Have a history of eating disorders
- Take medications that require food
- Have a history of low blood pressure
- Are significantly underweight
Additionally, if you experience dizziness, extreme fatigue, or feel unwell during a fast, stop immediately and eat something. Fasting should feel manageable, not miserable.
Your Action Plan
Starting today, you can begin supporting your brain's natural cleaning system:
- Tonight: Note what time you finish your last meal or snack.
- Tomorrow morning: Try to wait at least 12 hours before eating.
- This week: Gradually extend your overnight fast by 30-60 minutes each day.
- This month: Aim for a consistent 14-16 hour fasting window most days.
- Ongoing: Include autophagy-supporting foods in your eating window.
Remember, this is not about perfection. Even occasional fasting provides benefits. The goal is progress, not perfection—a gentle interruption to the patterns that may be contributing to your brain fog.
References
- Weber, M.T., Maki, P.M., & McDermott, M.P. (2014). "Cognition and mood in perimenopause: A systematic review and meta-analysis." Journal of Steroid Biochemistry and Molecular Biology.
- Cleveland Clinic. "Autophagy: Definition, Process, Fasting & Signs."
- Palmer, J.E. et al. (2025). "Autophagy, aging, and age-related neurodegeneration." Neuron.
- Glatigny, M. et al. (2019). "Autophagy Is Required for Memory Formation and Reverses Age-Related Memory Decline." Current Biology.
- Harrison Healthcare. "The Role of Autophagy in Maintaining Brain Health."
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This article is for educational purposes only and does not constitute medical advice. Please consult a qualified healthcare provider before making significant changes to your diet or lifestyle.