I am hoping someone can explain what is happening when I fast. So, I normally fast about 4 times a year for 5 days. Normally January, April, June and September. Last January I vowed never to do it again because of the cold. I also was hoping for the euphoric feeling around day 3/4 and have never had that. So I tried a 1,2,3 fast, in that I fasted for 24 hours had a meal fasted for 48 hour had a meal and then 3 days. I noticed that although I sat down and had a two course meal my ketones just kept getting higher. Why does this happen?
Next week I will be fasting for 3 days, but it might just be 3 x 24 hour fasts as the temperatures have dropped over the past week. Looking at the table I produced in October, what would be interesting markers to note down. The one I can think of is actually saying what I ate for those meals. Anything else?
It’s perfectly normal for ketones to rise during a multi-day fast. According to your chart, they maxed on day 5 of your fast. Most folks who do multiple-day fasts report that their ketones max at day 4-5.
Ketones result from the partial oxidation of fatty acids in the liver. As glucose/glycogen decreases during the fast time, your liver, other organs and muscles start utilizing fatty acids for fuel. At some point, the liver has too much fatty acid on hand to oxidize completely, so instead of just dumping it as excess fuel, partially converts it to ketones. The ketones then can be utilized as fuel by cells and organs that can’t or don’t oxidize fatty acids efficiently. Your brain, for instance, prefers ketones and will use just as much as you have available.
At some point, however, you reach homeostasis. In your case, that was on day 5. All that means is that everything finally started to get in sync with everything else. Stuff that can utilize fatty acids directly, are using it, stuff that uses ketones starts consuming as much as the liver synthesizes, so it no longer builds up in the blood.
Nothing to worry about.
Phinney and Volek published the following graph in The Art and Science of Low-Carbohydrate Living. As you will note, levels of ketones during fasting (labelled “starvation ketosis” on the graph) are typically higher than those seen in nutritional ketosis.
Thank you for your responses. Yes, I understand this, what surprises me is that my ketones continued to rise after eating. In my mind everytime I eat my ketone level should return to my normal level of about 0.5, not continue to rise. To me it looks like an unbroken fast, that I have not sat down and had a two course meal.
It looks like if I eat at 24 hours, 48 hours and it is like I haven’t eaten, I could do a longer fast. I don’t see the point though as I do an extended fast for the autophagy. I presume if I eat, I am restarting the process of autophagy even if my ketones continue to rise. For some reason it is easier to fast in this 1,2,3 day pattern, than five continous days.
Remember, ketones are a measure of fat burning…including the fat you eat. If you fast and then eat a high fat diet, your body will quickly break down that fat producing ketones in large bunches . For example, when NOT fasting, if I eat a very large amount of fat, my ketones might jump up to 3 for a few hours, but then fall back down to 1 or so as the food gets digested.
Also, what happens is that it takes a while to “clear out” the ketones. For instance, you have high ketones from fasting, and you start eating and make even more ketones. The ketones “build up” because there’s no where to go immediately. Dave Feldman has some nice graphs on his site where he shows this - he eats higher calorie, and his ketones shoot up for a while, and those calories go somewhere.