What is Ketosis?
Like most people, I did not know what ketosis was or whether having ketones in the body was a good thing or not. Ketosis by definition is the just the state of having ketones in our body. Since most of us have always eaten a carbohydrate-based diet, which uses glucose as the main fuel for our brains to run on, we did not know there was anything different. However, recently I have done a lot of research and found a huge body literature supporting the multiple benefits of having ketones in our bodies and using it for fuel instead of glucose.
I recently had the honor to listen to Dr. Stephen Cunnane, one of the leading researchers on nutrition and brain development, speak on his research about ketones as fuel for the brain. I have a few takeaways from that talk and from his recent article, published in Frontiers in Molecular Neuroscience that I would like to share to, hopefully, help show that having ketones in our bodies is indeed a good thing
Ketones are the preferred fuel source for the brain
It has been known since the 1960s, that ketones are the alternative fuel source, instead of glucose, for the brain. Dr. Cahill at that time showed that the liver would produce ketones when glucose levels were low, as a way of survival during times of fasting or starvation.
The amount of ketones that are taken up into the cells of the brain is directly related to the number of ketones that are present in the blood. Such that, the more ketones that are present in the blood, the more ketones will be taken up into the brain to be used. This is different than glucose, which is pulled into the brain cells based on the brain’s energy needs. Glucose also requires the presence of insulin to open the door for glucose to get into the cells (which is an issue in some neurological disorders such as Alzheimer’s Dementia).
In adults, the liver only produces ketones when glucose supplies are low, so ketones and glucose have not been available at the same time. Now that exogenous therapeutic ketones have been developed, your body can actually have ketones present even when glucose is also around. Thus, the body potentially now can have two different fuel sources in the body at the same time. So which one does the brain prefer? Dr. Cunnane researched just that question, and with the use of PET scans to show the amount uptake of glucose and ketones in the brain. He found that that amount of glucose utilization in the brain decreases as the availability of ketones to the brain increases. I.e. if the energy needs of the brain are being meet by ketones, glucose uptake decreases. Thus when ketones are around, they are actually the preferred energy substrate for the brain.
Ketones are essential to the developing infant’s brain
Ketones are essential to the developing infant. In the neonatal brain, there is insufficient glucose available to meet the very high-energy needs of the growing brain thus; it must rely heavily on ketones for fuel. Ketones are not only needed as a fuel but they are also the main substrate needed for brain lipid synthesis (brain development). Even after the infant is born the infant’s brain relies on ketones for fuel. Thus, the infant remains in a sustained state of ketosis. This ketosis is not a function of food restriction (or low glucose levels) but is due to the medium chain fatty acids (MCFAs) that are supplied from the breast milk (and some formulas). The MCFAs are then stored in the infant’s adipose tissue. After breastfeeding ends, the adipose tissues provide will enough fats for ketones to be produced for many months.
So, in summary, being in ketosis is very natural. It is the body’s way to be protective of our brain during times of starvation or fasting. It is also probably also the diet of our ancestors. It is also a very natural state since we are born in ketosis and with breast milk stay in ketosis throughout infancy. Lastly, our brain actually prefers ketones over glucose. Are you ready to see how good your brain feels with it is fueled with ketones?