I need help understanding BG levels while fasting

I'm 55 years old, male, reasonably fit. Diagnosed T2 diabetic in 2019 with an A1C of 7.9%. Found Dr Jason Fung while researching T2 diabetes, quickly moved on to OMAD and dirty keto which I've been doing for the last 2 years. A1C is now 6.3%, I've lost 15Kg and now weigh 94Kg. I'm 200cm so my BMI is 23.5 and my height to waist ratio is 47%. So, not even close to obese or even overweight. I exercise every day for at least an hour at aerobic which burns \~900 calories. On alternate days I add weight training. for 30 mins or so. I figure BMR is about 2000 so I think I'm looking at about 3500 TDEE. My confusion stems from a current exploration with a Dexcom G6 CGM. I wanted to figure out what effect different foods have on my BG and also, what effect different intensity exercise and at different times had on my BG. The data from the G6 is interesting when combined with my last years of A1C results which all hover around the 6.1 to 6.4% range. What the G6 shows me is that even after 23 hours of fasting, my BG is still often 6.5 to 7.5 mmol/L. In fact, the only time it really drops below 5.6 mmol/L is after about 15 mins of aerobic exercise when it will sometimes go to 4.8 or so before coming back up to 6.3+ within an hour of ending exercise. Everything I have read suggests that with a permanent OMAD schedule, healthy but not total keto diet and the amount of exercise I do, I shouldn't be insulin resistant, especially 2 years into it. Can anyone help me understand what is going on?

Answer

I figure an update is due.

I watched the video link posted by u/MindfulChimpboy and for whatever reason, it was a game-changer. I’ve done 3 and 5 days fasts before I got the G6 but after watching the video I decided to just run another 3 day fast and see what happened.

u/traktoriste - I discovered something. I’ve been following OMAD for a couple of years but the video reset my thought that this was ‘fasting’ as opposed to ‘time-restricted eating’. Whatever we call it. Dr. Jamandas explains clearly that it is ‘maintenance mode’.

So, my last meal was Tuesday at 4pm. Wednesday at 4pm my BG is 6.9 and has been in the 6+ range all day following the normal exercise dip. By 6pm, my BG is 4.9! For some reason, it dropped off suddenly and stayed below 5.9 over the next 24 hours. As simple as I can make it, it takes longer than 24 hours for my BG to drop; maybe I have become accommodated to an OMAD cycle?

I’m now trying to find info on whether a 3 day fast each week is sustainable or necessary.

ADDITION:

I didn’t understand u/contactspring comment ‘Your body adapts’. What I have come to understand using the G6 data over the last 72 hours is that my body had adapted to the OMAD schedule. I hadn’t realised of considered that my body adapted to it pretty quickly - in the first 4 months - then just sat quite happily making no progress for 20 months. I’m sure the off 3, 5 and 7 days fast over that time shook it up for a bit but then it simply reverted back to what it knew which was OMAD.

Things I noticed over the last 3 days: 1) the first 24 hours, nothing changed because my body assumed that I would eat. When that didn’t happen, BG dropped pretty quickly but wasn’t as stable over day 2 as it has been over day 3. By the end of day 2, I was going for hours with hardly any variation in readings and those were 4.4 to 4.6 mmol pretty constantly, even overnight when my BG is usually at its highest following a 4pm meal.

Day 3 has been rock solid, 4.4 to 4.6 with a quick drop to 4.2 when I drink a pint of water then back to 4.4. I’ve started on some bone broth to break the fast and I’ll eat tonight and over the weekend and see what happens. Sunday will be my last meal and I’ll do another 3 day next week and see what happens.

Hopefully, this thread is useful to others in this situation in the future.

Answer

Dr. Fung is awesome but I found that Dr. Pradip Jamandas really clearly explains what is happening with BG levels and how to win the war on type 2.

Here’s one of his talks. https://youtu.be/RuOvn4UqznU

I took my a1c from 6.7 to 5.4 in just 3 months. It can be done. Eat clean whole foods, nothing processed and lots of vegetables and fruit along with the meat. I gave up the keto as it gets to boring for me and added fruits, after that no craving for sweets and satiated with what I was eating during the day. I have only had 2 cheats so far this year because i don’t even think about it, just a slice of cheesecake.

Good luck

Answer

Excellent thread and I really appreciate the follow up! Very interesting stuff all around. I think adding Ivor Cummings to your portfolio of information advisors would be helpful as well as Dr. Malcolm Kendrick, all of these guys are right in line with Dr.Jamandas , Dr. Fung, Dr. Lustig good stuff all around, I also want to mention Dr. Panda with regards to circardian rhythms is also very good at helping put together the whole jigsaw puzzle!

Answer

My A1C results are 6,5% and although I have always loved prolonged fasts and I still do 24hr fasts every week, I noticed it doesn’t help for my BG. And I hate this feeling that actually fasts like that can ruin my progress. My morning BG is just higher than those days when I eat several hours before sleep.

I do intermittent fasting, too. It seems that the issue for me is with longer fasts (longer than 20hrs).

Maybe liver hates us and dumps glucose if it doesn’t get it from food anyway. Have you heard of Somogyi effect? Body has a lot of mechanisms to raise glucose if it goes low.