I’ve been practicing some form of Fasting (Intermittent, Extended) for over 20 years. I have found metabolic, cognitive and anti-aging benefits from simply not eating food for periods of time.

Recently, I completed a 7 Day Fast and decided to document my Fast and test my Glucose and Ketone levels daily (and calculated my Glucose-Ketone Index) in order to see if I would find a connection between blood levels and how I felt overall.

Daily I drank Matcha Green Tea with Lemon and Electrolytes.

DAY 1

Blood Levels
Glucose - N/A
Ketone 0.8
GKI - N/A

I had run out of glucose testing strips, so I didn’t test my glucose on day 1. Since I was already eating a well-formulated ketogenic diet I was already in a state of ketosis, which makes Fasting easier in my opinion.

I also happened to be on Day 1 of my period. Which is the best day for me to start a fast. The worst? Any day a week before my period where I want to eat ALL the things.

I did not work out, I usually do not work out on the first day of my period. I have a lifelong battle with Endometriosis (another post all-together) and that’s one of the ways I deal with it.

Weight - No Change
Mood - Emotional, Tired

DAY 2

Blood Levels
Glucose - 81
Ketone - 2.3
GKI - 1.95

Just 24 hours, and what a huge difference in my ketone levels. Usually the first two days are the hardest when I am fasting, the feelings of hunger are at their highest for me.

I did a morning HIIT Spin class and didn’t die. I had energy, but did not push the intensity as I would normally and would back-off when necessary. Since I sweat - A LOT- I supplemented my water with electrolytes.

I lost 5lbs on the scale, but as a long-time fasting practitioner, I intellectually know this is all water weight. But emotionally, I feel that 5lbs is 5lbs off of my joints and body regardless of where it came from. NOTE: This first bit of weight loss will be negated once I start eating. I never “count” it as bonafide weight loss when fasting.

Weight - Total Weight Down 5lbs
Mood - Steady

DAY 3

Blood Levels
Glucose - 64
Ketone - 2.3
GKI - 1.54

Another pound down, this is typical for me when fasting. A pound per day. Unless I am fasting beyond 7-10 days, where the weight loss slows.

My ketone levels did not increase, but my glucose levels decreased, which brought my GKI to a better range than Day 2.

My mental state is optimal, I do not feel any hunger, but I feel the cognitive hum that I’ve come to expect on Day 3 of fasting.

I did a Barre class, which is somewhat of a light day for me, so I added a light lifting session (Squat, Deadlift, Press) for 3 sets of 5 each.

Weight - Total Weight Down 6lbs
Mood - In the Zone

DAY 4

Blood Levels
Glucose - 74
Ketone - 4.3
GKI - 0.95

So an increase in glucose, but a much bigger jump in my ketones had my GKI in the therapeutic range. I’ve previously posted about GKI and what it means if you are interested.

I didn’t feel like working out physically, probably shouldn’t have doubled-up on Day 3. So I skipped the gym.

That said, my mind was buzzing with energy. I felt enormously creative and decide to push through a bunch of creative tasks that I had previously set aside for another day.

Weight - Total Weight Down 7lbs
Mood - Hyper-Focused

DAY 5

Blood Levels
Glucose - 77
Ketone - 2.0
GKI - 2.13

Not sure what happened to my levels. I’m still in ketosis but not as deeply as Day 4. My GKI is still in a good range. I wonder if it was the lack of physical exertion? This extra data point has an impact on my mental state because it doesn’t fit my narrative-I thought my ketone levels would keep going up up up. I make a mental note that there are too many variables to really know why and move on.

My stomach feels the nice flat emptiness that I’ve come to enjoy with fasting. There is no bloating or discomfort that happens when I eat certain foods. My digestive system is “quiet” and I love the silence. I have a LOUD digestive system and it can be embarrassing sometimes.

I go to Barre class, but I feel less strong, I can’t hold positions as I normally do, or do as many reps consecutively without breaking form… I chalk it up to the fasting process and try and be good with it.

Weight - Total Weight Down 8lbs
Mood - Frustrated

DAY 6

Blood Levels
Glucose - 61
Ketone - 2.8
GKI - 1.21

My GKI is better than yesterday, confirming for me that working out impacts my glucose and ketone levels.

I can tell that I’m done with this Fast, my body is showing me signs it’s time to start taking in something more than tea and electrolytes. I’m craving salt… big time. So I make some bone broth.

Intuitively, I also know that I need to break this fast methodically as my digestive system needs to start moving again. And I’ve made the mistake of jumping right into normal eating and let’s just say I was lucky I could run to my own bathroom multiple times.

Weight - Total Weight Down 9lbs
Mood - Ready to Eat Food

DAY 7

Blood Levels
Glucose - 82
Ketone - 2.7
GKI - 1.68

As anticipated, my glucose went up, I’m sure due to the bone broth. It’s still remarkable how I can have healthy glucose levels despite having experienced gestational diabetes and diagnosed with pre-diabetes. No signs of diabetes or metabolic syndrome just from just not eating food for a few days a year.

I don’t care what anyone says, 9lbs down, whether it was water or not, is still 9lbs off of my joints, tissues and body. I intellectually know that the first 5lbs I lost on Day 1 will return, and I’m good with that.

I feel amazing and like a Super Hero. My skin feels and looks renewed, my joints feel more flexible and my mental state is steady without emotional swings.

Weight - Total Weight Down 9lbs
Mood - Superwoman