Brain Fog and Keto: The Surprising Link You Need to Know About

Introduction

If you’ve ever walked into a room and forgotten why, struggled to find the right word, or felt like your thoughts were swimming through treacle, you’re not alone. Millions experience the frustrating haze known as brain fog - a state of mental fatigue that can sap focus, productivity, and even mood. While many factors can contribute, emerging research suggests the ketogenic diet may offer a surprising way to help lift the fog and restore clarity. In this article, we’ll explore how changing your brain’s fuel source could influence memory, focus, and cognitive performance - and whether keto might be worth considering for you.

Understanding Brain Fog: Causes and Contributing Factors

Brain fog is a non-medical term used to describe a cluster of cognitive symptoms such as forgetfulness, mental fatigue, difficulty concentrating, and slower processing speed. People often liken it to walking through thick fog, where clarity and sharpness are dulled.

The causes can be varied and may overlap. Lifestyle factors such as poor diet, inadequate sleep, and dehydration are common contributors. Chronic stress and hormonal fluctuations can also impair cognitive function, as can underlying medical conditions like hypothyroidism, autoimmune disease, and metabolic disorders.

A growing area of interest is the role of neuroinflammation - low-grade, chronic inflammation affecting the brain. Diets high in refined carbohydrates and ultra-processed foods can cause repeated blood sugar spikes and crashes, which not only impair focus but can also drive inflammation. Sleep deprivation and long-term stress further compound the problem, elevating cortisol and disrupting normal neural repair processes. For many, dietary shifts such as a ketogenic diet may help by supporting a more stable energy supply to the brain, improving metabolic health, and reducing inflammation.

What Is the Ketogenic Diet?

The ketogenic diet is a high-fat, moderate-protein, very-low-carbohydrate eating approach originally developed in the 1920s as a treatment for epilepsy. Its goal is to shift the body from using glucose as its primary fuel to producing and using ketones from fat metabolism - a state called ketosis.

Typical macronutrient ratios are roughly 70-75% fat, 20-25% protein, and 5-10% carbohydrate. This substantial carbohydrate restriction depletes glycogen (stored glucose), prompting the liver to produce ketones. These ketones can cross the blood-brain barrier and act as an efficient, stable energy source for the brain.

A well-formulated ketogenic diet prioritises healthy fats (avocados, nuts, seeds, olive oil, oily fish), adequate but not excessive protein (meat, poultry, fish, eggs, dairy), and a wide variety of low-carbohydrate vegetables for micronutrients and fibre.

How the Ketogenic Diet May Support Brain Health

The potential brain benefits of keto appear to arise from several mechanisms:

1. Reducing inflammation - By limiting refined carbohydrates and sugars, keto may help lower inflammatory signalling in the brain. Chronic inflammation has been linked to cognitive decline and mood disorders.

2. Stabilising blood sugar - Fewer spikes and crashes in glucose mean a more consistent energy supply to the brain, which may improve focus and reduce fatigue.

3. Neuroprotective effects of ketones - Ketones have been shown in research to support mitochondrial function and reduce oxidative stress.

4. Increased BDNF production - Ketosis may boost brain-derived neurotrophic factor, a protein essential for neuronal growth, plasticity, and resilience - important for learning and memory.

These effects combined may help explain why many people experience improvements in mental clarity and focus when following a ketogenic diet.

Transitioning to a Ketogenic Diet: Practical Tips

Changing to a ketogenic diet is a significant shift. A gradual approach often makes the transition smoother. Here's how:

• Reduce carbohydrates progressively while increasing healthy fats to allow the body to adapt.

• Support electrolytes - sodium, potassium, magnesium - to minimise "keto flu" symptoms such as headache, fatigue, or irritability.

• Stay well hydrated - the body will initially lose fluids as carbs are restricted.

• Plan meals in advance and keep keto-friendly snacks handy

• Track intake initially (using an app such as Carb Manager) to ensure you are within your carbohydrate target and meeting nutrient needs.

• Measure ketones - ideally using a blood meter. We like Ketomojo.

Foods to Prioritise and Avoid on Keto

Focus on:

• Healthy fats: avocados, olive oil, nuts, seeds, coconut oil, oily fish

• Moderate protein: grass-fed meat, poultry, eggs, dairy, wild-caught fish

• Low-carb vegetables: leafy greens, cruciferous veg, courgettes, peppers, asparagus

• Berries: blueberries, raspberries, strawberries - in moderation

Limit or avoid:

• Grains, legumes, starchy vegetables, most fruits

• Refined sugars, ultra-processed foods, sweetened drinks

Risks and Considerations

While many people tolerate the ketogenic diet well, it’s not suitable for everyone - and the safest way to start is with guidance from a nutritional therapist or suitably qualified healthcare practitioner.

Although keto is generally considered safe for most healthy adults, there are important absolute contraindications and groups for whom it is not appropriate:

• Medical conditions - Pancreatitis, liver failure, gallbladder disease, certain rare metabolic disorders

• Medications - Some prescription drugs, including certain SGLT2 inhibitors (used for type 2 diabetes), pose serious risks if combined with a ketogenic diet. Always check with your practitioner first.

• Life stage and health status - Should not be attempted during pregnancy or breastfeeding, in individuals with a history of eating disorders, or in children (unless under strict medical guidance, e.g. for epilepsy).

  
  

Other important considerations:

• Medication adjustments - Blood sugar-lowering drugs, blood pressure medication, and other prescriptions may need altering to avoid adverse effects.

• Lipid profile changes - LDL cholesterol can rise in some people, so regular monitoring is advised.

  
  

For these reasons, do not start a ketogenic diet without first confirming it is safe and appropriate for you, and ideally follow it under professional supervision - particularly if you have an existing health condition or take regular medication.

Conclusion

Brain fog can have many underlying causes, and nutrition is just one piece of the puzzle. But by providing a stable, efficient fuel source for the brain, reducing inflammation, and supporting neuronal health, a ketogenic diet may help you to think more clearly and feel more focused.

If you do decide to try keto, it should be well-planned, personalised, and supervised – so you avoid common pitfalls, keep it safe, and make it work for your unique needs.

If you’re curious about whether keto could be part of your brain health strategy, we can guide you through the process step-by-step – from safety checks to personalised food plans and ongoing support. Book a consultation with Anna, our Clinic Manager to explore your options.