What is the Ketogenic Diet?
As the name suggests, the ketogenic diet is a diet that GENerates KETones. Ketones are fatty-acid metabolites created by the liver as an alternative fuel source during periods of starvation or carbohydrate restriction.
Another name for the ketogenic diet is the keto diet, which can be further shortened to just keto.
The process of creating ketones in the liver is called ketogenesis.
The metabolic state of generating ketones is referred to as ketosis. If you’ve removed enough carbohydrates from your diet long enough, your liver will begin ketogenesis, start breaking down fatty acids to create ketones, and you will be “in” ketosis.
What are Ketones?
Again, ketones are fatty-acid metabolites created by the liver as an alternative fuel source during periods of starvation (in general), but particularly during periods of carbohydrate restriction.
I.e., if you restricted your carbohydrate consumption– to roughly no more than 20 to 40 grams per day– your liver will break down fat and convert it into ketones to supplement your energy requirements in the absence of carbohydrates.
The human brain, at a minimum, requires approximately 50 grams of carbohydrates (i.e., glucose) a day to function. That’s not to say that if you don’t eat 50 grams of carbohydrates a day that it will cease to function– your body is more than capable of creating those 50 grams of carbohydrates/glucose from fat and protein– but it does mean that your brain requires an alternative fuel source to supplement those 50 grams of carbohydrates.
For someone following the USDA recommended dietary guidelines, that is to say eating carbohydrates and not in ketosis, their body runs entirely off of two fuel sources: fatty acids and glucose. Fatty acids, however, are unable to cross the blood-brain barrier and fuel the brain. Hence, the brain is almost entirely reliant on glucose to meet it’s energy needs.
Make no mistake, your brain will get it’s minimum 50 grams of glucose a day: either by dietary consumption of carbohydrates, manufacturing those 50 grams from fat and protein, or some combination of the two. Those 50 grams of glucose by themselves, however, are insufficient to meet all of your brain’s energy requirements and have to be supplemented with additional carbohydrates/glucose.
But what if you are following a ketogenic diet and are restricting carbohydrates? If fatty acids can’t cross the blood brain barrier and you aren’t supplementing those 50 grams of glucose with more dietary carbohydrates, how can you meet your brain’s energy needs?
In the absence of carbohydrates, your body will adapt to better utilize fatty acids as fuel. As previously mentioned, however, those fatty acids are unable to cross the blood brain barrier. Thus the need for the liver to break down additional fatty acids to create ketones which are perfectly capable of crossing the blood brain barrier and meeting your brain’s energy requirements.
So even in the absence of carbohydrates, your body will still run on fatty acids, glucose and ketones.
The vast majority of the global population eats carbohydrates; carbohydrates are a relatively inexpensive energy source; carbohydrates, especially simple sugars, taste great, why would anyone want to remove them from their diet? What advantage does carbohydrate restriction in general and ketogenic diets in particular provide?
Stay tuned: Why do Keto?