Alzheimer’s and Insulin Resistance: How to Protect Your Brain Through Nutrition

Alzheimer’s disease is often explained through plaques and tangles in the brain. But new science shows another powerful driver: insulin resistance. Some researchers now call Alzheimer’s “type 3 diabetes” because the same metabolic dysfunction seen in type 2 diabetes is also found in the brain. Understanding this connection gives us a clear path for prevention and support.

How Insulin Resistance Affects the Brain

Insulin is more than a blood sugar hormone. In the brain, it helps neurons absorb glucose for energy, regulates neurotransmitters, and supports memory. When insulin resistance develops, brain cells can no longer use glucose efficiently. Neurons starve, inflammation rises, and damage begins to spread.

Studies confirm that people with type 2 diabetes face a much higher risk of dementia and Alzheimer’s. High blood sugar, visceral fat, and chronic inflammation all feed into the same cycle of brain dysfunction.

Why Ketones Help

The brain can run on two fuels: glucose or ketones. When insulin resistance blocks glucose, ketones bypass the problem. Ketones are cleaner fuel, producing more energy and fewer free radicals. Research shows that raising ketone levels through diet or MCT oil improves memory and processing speed in people with mild cognitive impairment. This makes ketogenic strategies one of the most promising tools for brain health.

Expert Perspectives

• Dr. Paul Mason explains Alzheimer’s as a metabolic disease and recommends a low-carb, ketogenic diet to reduce insulin resistance and provide ketones for brain energy.
• Bart Kay describes insulin resistance as the body’s protective response to chronic fuel overload. He warns against eating both high sugar and high fat together and supports low-carb or carnivore diets to reduce metabolic stress on the brain.
• Dr. Georgia Ede highlights insulin resistance as the root of “garden-variety” Alzheimer’s and advises lowering carbohydrate intake, eliminating processed foods, and prioritizing whole-food fats and proteins.
• Dr. Suzanne de la Monte, who coined the phrase “type 3 diabetes,” shows how impaired insulin signaling in the brain directly causes Alzheimer’s pathology.
• Dr. Stephen Cunnane demonstrates that ketones restore brain energy in early Alzheimer’s, improving cognition when glucose use declines.

What You Can Do to Prevent or Slow Alzheimer’s

Research is still growing, but evidence strongly supports targeting insulin resistance. These steps can help lower risk or support someone already showing early signs:

1. Reduce sugar and starch
   Limit foods that spike blood sugar—breads, cereals, pasta, juices, soda, and sweets. Replace them with protein and healthy fats.

2. Choose whole foods
   Base meals on meat, fish, eggs, non-starchy vegetables, nuts, and natural fats like olive oil, butter, or avocado. Avoid processed foods made with seed oils and hidden sugars.

3. Support ketone production
   A ketogenic or low-carb diet, intermittent fasting, or MCT oil can raise ketone levels and provide the brain with reliable energy.

4. Improve insulin sensitivity
   Maintain a healthy weight, reduce visceral fat, and stay active. Even light daily activity improves how the body uses insulin.

5. Track your markers
   Monitor fasting glucose, HbA1c, and, if possible, fasting insulin. These numbers help measure progress in reducing insulin resistance.

6. Consider timing of meals
   Time-restricted eating gives the body a break from constant insulin spikes and can help restore metabolic flexibility.

Why Metabolic Health Is Key

Alzheimer’s does not happen in isolation. The same metabolic dysfunction that causes obesity, fatty liver, type 2 diabetes, and heart disease also fuels dementia. At the center of all of these conditions is insulin resistance. By addressing it early, you protect not only your brain but your entire body.

Final Thoughts

Alzheimer’s is one of the most feared diseases of aging. While there is no single cure, evidence shows that taking control of insulin and metabolic health changes the trajectory. Lower carbs, focus on whole foods, use ketones as brain fuel, and reduce visceral fat. These practical steps can help protect your memory and may support loved ones already showing early signs.

References

1. de la Monte SM, Wands JR. Alzheimer’s disease is type 3 diabetes—evidence reviewed. J Diabetes Sci Technol. 2008.

2. Arnold SE, Arvanitakis Z, Macauley-Rambach SL, et al. Brain insulin resistance in type 2 diabetes and Alzheimer disease. Alzheimers Dement. 2018.

3. Cheng G, Huang C, Deng H, Wang H. Diabetes as a risk factor for dementia and mild cognitive impairment: a meta-analysis. Int J Geriatr Psychiatry. 2012.

4. Cunnane SC, Courchesne-Loyer A, Vandenberghe C, et al. Can ketones compensate for deteriorating brain glucose uptake during aging? Ann N Y Acad Sci. 2016.

5. Krikorian R, Shidler MD, Dangelo K, Couch SC, Benoit SC, Clegg DJ. Dietary ketosis enhances memory in mild cognitive impairment. Neurobiol Aging. 2012.

6. Craft S, Claxton A, Baker LD, et al. Effects of intranasal insulin in Alzheimer’s disease and mild cognitive impairment. Arch Neurol. 2012.

7. Mason P. Lectures and interviews on dementia and nutrition.

8. Kay B. Commentary on insulin resistance and metabolic overload.

9. Ede G. Clinical commentary and lectures on low-carb diets and brain health.

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Disclaimer: The content shared here is for informational and educational purposes only and should never be taken as medical advice.

In writing this blog post, my goal is to distill research findings into a clear, approachable format that encourages critical thinking and empowers you to make informed decisions about your health.