The Role of Intermittent Fasting in Ketosis – Part 5

The ketogenic diet has been effective in my practice in the treatment of obesity and chronic disease without hunger or deprivation.

– Dr. Keith Runyan


Since I wanted to see what changes were happening to me during the entire week, I decided to test blood ketones and blood sugar every waking hour on the hour while observing everything that was happening in my normal routine.

This would allow me to assess precisely how the fast was affecting all my numbers and state of health in real time. I promised myself and my wife that if at any point I started to feel bad beyond just simple hunger, or if my blood sugar dipped into the lower 50s for more than a couple of hours, I would end the experiment immediately.

During my first couple of days without food, my blood sugar began dropping slowly, until the bottom fell out in the early afternoon of the third day. That’s when my blood sugar hit 59 for over two hours—and it was accompanied by a headache. Other than that, I felt pretty good. But even when my blood sugar rose back into the upper 60s again, my headache persisted.

My blood ketone levels followed a similar pattern but in the inverse. I saw normal readings of around 1.0 to 1.5 millimolar in the first couple of days, and then BOOM: it was 4.6 after forty-nine hours of fasting and slowly ticked up from there, to a high of 5.8 millimolar seventy-one hours into the fast.

This coincided with my blood sugar dipping down to 59 for a couple of hours. As I’ve stated before, I wasn’t at all worried about my blood ketones going that high because it coincided with a simultaneous drop in my blood sugar levels (I can’t emphasize this point enough: diabetic ketoacidosis occurs only when both blood ketones and blood sugar are elevated to extremely high levels; nutritional ketosis produces higher blood ketones and lower blood sugar).

Because of the persistent headache, I decided to officially end the fast at 5:30 p.m. on the third day. Within an hour of eating a pretty sizable meal, the headache completely disappeared. I’m thinking now that my electrolyte balance was off; the bouillon cubes were a lot more effective in helping me sustain the fast in 2011 than I realized.

It was a lesson learned for the next time I attempt to do a one-week fast. I can’t help but wonder how much higher my blood ketones might have gone had I continued the fasting experience for the entire seven days. Incidentally, the night after I ended my three-day fast, I had difficulty sleeping, waking up after just a few hours.

Here are a few observations I made after my three-day fast was over :

  • My first meal after fasting for seventy-two hours was pretty substantial.
  • Despite eating a large amount of food, hunger persisted for a while, and I had to resist the urge to keep eating and eating.
  • For a while after the fast, I felt hungry more often than I did before the fast began.
  • Morning fasting blood sugar levels rose into the 90s in the days that followed the fast.
  • Blood ketones dropped back down to normal within three days.
  • When I went back to the gym, I still had full strength.
  • My weight predictably rose several pounds after the fast ended.
  • My sleep took a couple of days to become uninterrupted again.
  • My mental clarity remained unchanged throughout.

You don’t need to completely fast for days on end when you get into ketosis; I did it just to see what would happen. My conclusion is that you can get all the benefits of fasting by letting it happen naturally when you consume a low-carb, moderate-protein, high-fat diet with ample calories. Ketones give you the luxury of fasting that way, without even thinking about it.

Perhaps what you’ve read so far has spurred some questions in your mind about ketones that have not yet been addressed. Coming up in the next chapter, you’ll get answers to some of the most frequently asked questions about keto.

Key Keto Clarity Concepts :

  • Periods of fasting can help increase the production of ketones.
  • The idea of going without food over a period of hours seems crazy, but it’s not.
  • Intermittent fasting (IF) is a popular strategy for weight loss and health.
  • Fasting is a natural, spontaneous response to higher levels of ketones.
  • There’s no such thing as needing to eat three square meals a day.
  • Your meals should be substantial enough that you only eat once or twice daily.
  • Periods of fasting will help you determine your keto fitness level.
  • If you are hungry, eat something.
  • Eat when hungry, drink when thirsty.
  • Hunger is a subjective feeling and you need to determine what it is for you.
  • Not getting adequate salt on your ketogenic diet can make you feel hungry.
  • Glorifying hunger is insane.
  • When you are craving processed carbohydrates, eat fat and protein instead.
  • How much and when you eat is a personal decision.
  • Pay attention to the non-hunger cues that you associate with eating.
  • Comfort food doesn’t have to be full of carbs; bacon can be your new comfort food.
  • Gurgling or growling noises in your stomach are not signs of true hunger.
  • Closely observe how you feel while fasting and adjust mealtimes accordingly.
  • Prolonged periods of fasting raise blood ketones and lower blood sugar levels.
  • You don’t need to completely fast for days to get the benefits of fasting.

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