My 7 day fast compared to my 10 fast (limits of Dexcom CGM achieved)

(Michael) #1

I will update my recent EF results in here once it is complete and compare to my previous fast tomorrow - the resulting are surprisingly different. However, I thought something was pretty funny (and disturbing!) that I wanted to share first. Last night (at hour 148 or so) I put on a CGM to track my glucose during my last fasting night and then to see what happens when I start eating later tonight and for the next 10 days on carnivore with noticeable protein differences in my diet.

First off, the Dexcom 6 overrides silent options for “urgent low” glucose readings and beeps every time your blood sugar goes below the minimum, which you can set at a lowest value of 3.1 mmol/L (I am sure mostly for people taking insulin). After a two hour warmup, it started taking readings at 12:30 am (I calibrated and tried to go back to sleep) and it started beeping by 2:30 am when my glucose fell to 2.9. It beeped all damn night every 30 minutes. From 3:30 - 5 am my glucose reads as “LOW” and Dexcom uses a value of 2.2 mmol/L for calculations, but as it was a perfectly straight line for 90 minutes (never happens). I am sure it dipped below that value quite a few times in that timespan and I reached the limits of the CGM. Who knows how low, but clearly lower than the monitor can measure accurately. I did not sleep well at all (nor did my wife who did not complain - but she did tell me to sleep somewhere else tonight - lol). Here is the CGM data - note the flatline in the middle.

Yesterday I supplemented with Magnesium Aspartate, Dipotassium Phosphate, Disodium Phosphate and a pinch or two of salt. Today I am supplementing with Magnesium Aspartate, Tricalcium Phosphate, Zinc Picolinate, Potassium Chloride, Disodium Phosphate, 3X100 mg Benfotiamine.

(Bob M) #2

I forget what podcast I listened to, but they had a husband and wife who did a 7 day fast. They both had really low glucose, such that their Free Style Libres basically refused to work. I think they alarmed and said “low” or something similar. As in close to 30? But they both felt fine.

2.2 = about 40 US units.

That’s low, but I assume you feel fine.

(Michael) #3

I am surprised but I feel great today despite the lack of sleep. I am not sure if it is because I know I am eating later today, but I am doing wonderful. I could not work out yesterday, so I am going to do an hour of weightlifting soon in preparation for refeed. You will find my side by side fast comparison interesting - I will wait until I take my last fasted readings before eating tonight to post.

(Old Baconian) #4

Would you have known there was a problem with your glucose if you had not been using the monitor? If not, then you are fine. But if you ever experience symptoms of hypoglycaemia, then that is a very different issue.

Dr. George Cahill did an experiment on some fasting research subjects, using a hyperinsulinaemic euglycaemic clamp, and drove their serum glucose down to levels that would have caused coma or death, had their ketones not been elevated from fasting. The subjects were all fine; as Dr. Phinney jokes, it was the researchers who were having sweats and palpitations. It was a highly unethical experiment and would not be permitted by an IRB today, but it yielded very illuminating information.

(Michael) #5

Alright, here are the comparisons. Unfortunately I did not take glucose/ketone measurements for the first 72 hours since the previous fast my numbers were not good enough to be interesting. I have modified the chart from that session to show (essentially) the same hours for easier comparison. It is clear my blood glucose falls much faster and lower than the previous fast. A clear indication that the 10 day fast had a positive effect on my metabolism. I suspect this recent 7 day fast will also have a positive effect as well, but I was honestly surprised at the amount of effect on the 10 day fast. Previously 7 days to get a GKI < 1 and 10 to reach a GKI of 0.7, this time I already had 0.7 within 3 days (why I wish I had started measuring a bit earlier). It took until hour 179 to break 5 mmol/L for ketones on my first fast, but only 84 hours during the second fast. I definitely lost more weight the first fast, but I am getting a bit lean now, so no surprise there. I did not include the data for this morning, but after eating (500 mL bone broth, 1 12 oz steak and 8 pieces of bacon to break my fast) my GKI this morning was a little over one, my weight is 139.2 lbs and my BP was an excellent 92/62. I will post the 10 day CGM data in another thread once it is complete. Following is the excel data and the graph for each fast:

10-day Fast data/graph

Date Time Glucose bHB GKI Weight (in pounds) BP Hour into fast
4-Aug 10:19:00PM 157.6 1
7-Aug 11:49:00PM 3.9 2 1.95 74
8-Aug 8:09:00AM 4.8 1.9 2.53 151.4 83
8-Aug 10:29:00PM 4.0 3.1 1.29 153.4 97
9-Aug 8:39:00AM 4.1 3.8 1.08 150.0 107
9-Aug 12:39:00PM 4.1 3.6 1.14 111
9-Aug 10:19:00PM 3.7 3.6 1.03 151.6 121
10-Aug 9:39:00AM 4.8 4.4 1.09 149.2 132
10-Aug 9:49:00PM 4.2 4.2 1.00 149.4 144
11-Aug 8:55:00AM 5.1 4.5 1.13 146.8 155
11-Aug 10:12:00PM 3.7 4.3 0.86 147.6 169
12-Aug 8:35:00AM 4.5 5.2 0.87 146.6 179
12-Aug 9:19:00PM 3.8 4.2 0.90 147.6 192
13-Aug 9:35:00AM 4.6 5.4 0.85 145.0 204
13-Aug 11:19:00PM 4.3 4.1 1.05 147.4 218
14-Aug 9:35:00AM 5.6 5.7 0.98 145.0 228
14-Aug 11:09:00PM 3.7 5.2 0.71 146.8 242


7-Day Fast

Date Time Glucose bHB GKI Weight (in pounds) BP Hour into fast
15-Sep 8:00:00AM 142.2 125/80 12
16-Sep 8:00:00AM 140.4 115/67 36
16-Sep 8:00:00PM 141.6 48
17-Sep 8:00:00AM 139.8 105/68 60
18-Sep 12:00:00AM 3.0 4.3 0.70 141.8 115/69 76
18-Sep 8:00:00AM 3.9 5.3 0.74 139.8 107/68 84
18-Sep 8:00:00PM 3.3 3.7 0.89 140.8 104/65 96
19-Sep 8:00:00AM 4.6 4.4 1.05 138.6 111/72 108
19-Sep 8:00:00PM 2.9 4.9 0.59 139.8 109/66 120
20-Sep 8:00:00AM 3.6 4.6 0.78 137.6 101/66 132
21-Sep 12:30:00AM 3.2 5.7 0.56 137.8 99/62 148
21-Sep 8:00:00AM 3.6 5.3 0.68 137.2 98/63 156
21-Sep 6:00:00PM 3.1 4.9 0.63 137.6 101/66 166