You might have heard that carbohydrates are necessary to provide glucose to fuel the brain and avoid hypoglycemia.
It’s an old way of thinking, and it’s just not true scientifically.
The “brain needs carbs” idea is only true if you eat a very high carb diet (as most dietary experts will tell you to do) and your brain has no ketones to use as an alternative fuel.
Remember, a high carb diet interferes with ketosis; in other words, carbs kick you out of ketosis (burning fat for fuel).
Once your body is in ketosis and become fully keto-adapted:
- The skeletal muscles burn fatty acids preferentially.
- The brain switches to using ketone bodies for over half of the fuel it needs and less glucose is needed since ketone bodies are being used as an alternative fuel.
- This small amount of carbohydrate (glucose or blood sugar) needed to fuel the brain during keto-adaptation can be generated internally by your wonderful liver from glycogen stored in the liver. And if necessary, your body can also make glucose from the protein in your food.
In summary, you can survive on zero dietary carbs, and the brain does perfectly well. It’s a highly evolved strategy for survival, especially back when we had very little access to carbs.
The ability of the human brain to use ketones is probably one of the most important evolutionary adaptations that account for our bigger brains than other animals.
The dietary change to increase carbohydrates is profoundly negative for our generation. The diet instigates changes in blood sugar and our ability to regulate our blood sugar, implicating insulin. This dietary change has paved the way for people to begin eating food that has very little nutritional value.
If you honestly start to log your daily food intake, you are sure to be surprised by how many carbs most people are consuming on a daily process.
In a typical Keto diet, processed, out-of-the-box/can/bag carbs are religiously banned, but real food carbohydrates like vegetables are gladly included.
While some vegetables have more carbs than others, you can eat a ton of vegetables and still stay within the 30 to 40 grams total carbohydrate range.
Good carbs should be fiber rich and nutrient dense, providing prebiotics for your microbiome. This includes jicama, Mexican yams, dandelion greens, garlic, onions, leeks, and asparagus. These are mostly digested by our gut bacteria. Our bacteria then replicate, make vitamins, have a roll in neurotransmitter production, balance our production of vitamin k and b vitamins, and help to keep our gut epithelium intact – reducing permeability of the gut lining which is fundamental to the process of inflammation.
I strongly urge you to check out this amazing book The Grain Brain Whole Life Plan: Boost Brain Performance, Lose Weight, and Achieve Optimal Health by David Perlmutter MD.
Here is a great interview on the subject of ketogenic diet, gut bacterial diversity and exercise for optimal brain health.