Brain Fog: What It Is, What It Isn't, and How to Clear It

October 22, 2025
Dr. Steven Lu
Chief Medical Officer | MBBS (hons) | DCH FRACGP
Brain Fog: What It Is, What It Isn't, and How to Clear It

Feeling foggy, forgetful or just not as sharp as you used to be? You might be experiencing something called "brain fog." It's a common complaint—especially among adults over 40—but it often gets chalked up to ageing. Here's the truth: brain fog isn't a normal part of getting older, and in many cases, it's a red flag for something deeper going on.

What Is Brain Fog?

Brain fog isn't a medical diagnosis, but it's a very real experience. It describes a set of cognitive symptoms like:

  • Trouble concentrating
  • Poor memory
  • Mental fatigue
  • Slow thinking
  • Difficulty finding words

It's like your brain is running through molasses. You know you're not functioning at your best, but you can't quite put your finger on why.

What Brain Fog Isn't

Brain fog is not dementia, and it's not an inevitable part of ageing. It also isn't "just tiredness." While fatigue can contribute, ongoing brain fog often signals deeper issues like blood sugar imbalances, chronic inflammation, or nutrient deficiencies.

Many people assume it's just a natural slowdown with age, but research tells a different story. Cognitive decline does increase with age, but so do preventable conditions like insulin resistance, hormone imbalance, and chronic stress—all of which can cause brain fog long before true age-related cognitive decline sets in.

Why It Gets Blamed on Age

It's easy to blame brain fog on getting older. After all, you're busier, more stressed, and maybe sleeping less than you did in your 20s. But while age is a risk factor for some conditions, it's often not the root cause of brain fog.

In fact, many symptoms attributed to ageing start decades earlier due to lifestyle, diet, and silent biological changes. For example:

  • Poor blood sugar control impairs mental clarity, even in non-diabetics.
  • Low B12, iron, or vitamin D can cause fatigue and cognitive dysfunction.
  • High cortisol from chronic stress shrinks the hippocampus—a part of the brain essential for memory.
  • Sleep disorders like sleep apnoea often go undiagnosed in adults.

Quick Wins to Clear Brain Fog Today

1. Swap refined carbs for protein at breakfast

Starting your day with cereal, toast, or juice? You’re setting yourself up for a blood sugar spike and crash, which can trigger brain fog.

  • Try eggs, Greek yoghurt, or a protein smoothie instead.

2. Take a 10-minute walk after meals

Post-meal walks help regulate blood glucose and insulin—major players in brain function.

  • Even a short stroll around the block can improve mental clarity.

3. Hydrate early and often

Dehydration is a sneaky contributor to poor focus and fatigue.

  • Aim for 2–2.5L of water daily, especially in the morning.

4. Get sunlight in the morning

Light exposure supports circadian rhythm and boosts mood-regulating neurotransmitters.

  • Try 15 minutes of sunlight before 10am, ideally while walking.

5. Cut back on ultra-processed foods

Studies show links between ultra-processed diets and worse cognitive function.

  • Stick to whole foods when possible. Your brain loves colour, fibre, and healthy fats.

How to Get to the Bottom of It

If brain fog persists, it's worth digging deeper. At Everlab, we’ve found the most common causes in high-functioning adults are:

  • Insulin resistance (even without diabetes)
  • Hormonal shifts (e.g. thyroid, testosterone, oestrogen)
  • Nutrient deficiencies (especially B12, D, and iron)
  • Inflammation (from gut issues, chronic stress, or lifestyle)
  • Sleep dysfunction (even mild)

A comprehensive check-up that includes blood biomarkers, cognitive screening, and metabolic analysis can help pinpoint the cause—and give you a personalised plan to fix it.

The Bottom Line

Brain fog isn’t just in your head — and it isn’t just about age. It’s a signal your body is out of balance. The earlier you catch it, the easier it is to reverse.

Simple changes to your diet, sleep, and daily routine can start clearing the fog fast. But for lasting clarity, the key is understanding what's really going on under the hood.

Want help uncovering the root cause? Everlab offers a comprehensive check-up designed to spot the early signals of decline—before they become disease.

Stay sharp. You’ve got a lot more life to live.

Feeling foggy, forgetful or just not as sharp as you used to be? You might be experiencing something called "brain fog." It's a common complaint—especially among adults over 40—but it often gets chalked up to ageing. Here's the truth: brain fog isn't a normal part of getting older, and in many cases, it's a red flag for something deeper going on.

What Is Brain Fog?

Brain fog isn't a medical diagnosis, but it's a very real experience. It describes a set of cognitive symptoms like:

  • Trouble concentrating
  • Poor memory
  • Mental fatigue
  • Slow thinking
  • Difficulty finding words

It's like your brain is running through molasses. You know you're not functioning at your best, but you can't quite put your finger on why.

What Brain Fog Isn't

Brain fog is not dementia, and it's not an inevitable part of ageing. It also isn't "just tiredness." While fatigue can contribute, ongoing brain fog often signals deeper issues like blood sugar imbalances, chronic inflammation, or nutrient deficiencies.

Many people assume it's just a natural slowdown with age, but research tells a different story. Cognitive decline does increase with age, but so do preventable conditions like insulin resistance, hormone imbalance, and chronic stress—all of which can cause brain fog long before true age-related cognitive decline sets in.

Why It Gets Blamed on Age

It's easy to blame brain fog on getting older. After all, you're busier, more stressed, and maybe sleeping less than you did in your 20s. But while age is a risk factor for some conditions, it's often not the root cause of brain fog.

In fact, many symptoms attributed to ageing start decades earlier due to lifestyle, diet, and silent biological changes. For example:

  • Poor blood sugar control impairs mental clarity, even in non-diabetics.
  • Low B12, iron, or vitamin D can cause fatigue and cognitive dysfunction.
  • High cortisol from chronic stress shrinks the hippocampus—a part of the brain essential for memory.
  • Sleep disorders like sleep apnoea often go undiagnosed in adults.

Quick Wins to Clear Brain Fog Today

Good news: you don't need to wait months to start feeling clearer. These quick, science-backed changes can make a noticeable difference in days or weeks:

1. Swap refined carbs for protein at breakfast

Starting your day with cereal, toast, or juice? You’re setting yourself up for a blood sugar spike and crash, which can trigger brain fog.

  • Try eggs, Greek yoghurt, or a protein smoothie instead.

2. Take a 10-minute walk after meals

Post-meal walks help regulate blood glucose and insulin—major players in brain function.

  • Even a short stroll around the block can improve mental clarity.

3. Hydrate early and often

Dehydration is a sneaky contributor to poor focus and fatigue.

  • Aim for 2–2.5L of water daily, especially in the morning.

4. Get sunlight in the morning

Light exposure supports circadian rhythm and boosts mood-regulating neurotransmitters.

  • Try 15 minutes of sunlight before 10am, ideally while walking.

5. Cut back on ultra-processed foods

Studies show links between ultra-processed diets and worse cognitive function.

  • Stick to whole foods when possible. Your brain loves colour, fibre, and healthy fats.

How to Get to the Bottom of It

If brain fog persists, it's worth digging deeper. At Everlab, we’ve found the most common causes in high-functioning adults are:

  • Insulin resistance (even without diabetes)
  • Hormonal shifts (e.g. thyroid, testosterone, oestrogen)
  • Nutrient deficiencies (especially B12, D, and iron)
  • Inflammation (from gut issues, chronic stress, or lifestyle)
  • Sleep dysfunction (even mild)

A comprehensive check-up that includes blood biomarkers, cognitive screening, and metabolic analysis can help pinpoint the cause—and give you a personalised plan to fix it.

The Bottom Line

Brain fog isn’t just in your head — and it isn’t just about age. It’s a signal your body is out of balance. The earlier you catch it, the easier it is to reverse.

Simple changes to your diet, sleep, and daily routine can start clearing the fog fast. But for lasting clarity, the key is understanding what's really going on under the hood.

Want help uncovering the root cause? Everlab offers a comprehensive check-up designed to spot the early signals of decline—before they become disease.

Stay sharp. You’ve got a lot more life to live.

Dr. Steven Lu
Chief Medical Officer | MBBS (hons) | DCH FRACGP

Steven is a specialist general practitioner, preventative health consultant, medical educator, healthcare entrepreneur and co-founder of Everlab. With 15+ years of clinical experience, and driven by his passion for preventive care outcomes, Steven is dedicated to personalised and innovative approaches to enhance well-being, extend human lifespan, and improve healthspan.