Glucose and Ketones after exercise

(Allison B) #1

Can anyone explain the science behind a rise in BG and also Ketones following a workout? I have recently added fasting workouts. My BG shoots up to between 120-130 and my ketones also rise, immediatly following my workout. I’ve been doing keto for 7 months

Ketone levels after my run
Blood measurements question
(Ethan) #2

my BG also goes up to 110-120 during a working, but ketone drop like a rock.

(Allie) #3

My ketones drop too, as they’re used as fuel for my workout

(Allison B) #4

Do you all workout in a fasted state?

(Ethan) #5

I work out in all kinds of states, including fasted and having just eaten.

(Allie) #6

I don’t normally.

(ianrobo) #7

I can understand BG rising and this ties in with the FASTER study as well but Ketones, no that seems very strange to me.

(Allison B) #8

Well this is something I found that explains my ketones rising after a workout.

Exercise has long been known to increase ketone production, even in people without diabetes. Increases in fat mobilization and increased blood flow to the liver during exercise promotes increased fat uptake to the liver and the conversion of fat first to acetyl-CoA and then to the ketone body acetoacetate. Acetoacetate can then convert to the two other ketone bodies – acetone and beta-hydroxybutyrate. These ketone bodies then leave the liver and can be used by muscle as energy.

(ianrobo) #9

I used to measure BG and Ketones before and after exercise by blood and never saw Ketones rise, actually the opposite. In fact the well adapted fat athlete should in fact have naturally very low levels.

(Allie) #10

Mine are always their lowest after exercise, right down to 0.1 sometimes

(ianrobo) #11

When testing and after anything above an hour I saw zero which means I was using them as produced then, that’s perfect. I would argue if you are seeing high levels you are not efficient in using them

(Duncan Kerridge) #12

I thought I’d try this out today, I tested just before I went swimming, immediately after and an hour after that. 1200m in the pool, about 30 mins hard swimming.

Before - BG : 70 K : 2.1
After - BG : 74 K : 0.8
+1 hour - BG : 65 K : 2.4

(Alex) #13

In my case - i get high BG and low ketones, but only when i do low intensity. During high intensity - i have high BG and ketones almost unchanged. I think I have read somwhere that during anaerobic exercises main fuel is BG, not ketones.

(Kyle Walker) #14

I too experience higher ketrone levels after a workout. This morning my fasted pre workout level was 2.3. it was 2.4 after 1 hour of cardio. There is some belief that if working out in an anaerobic state your body is taping the emergency glucose and not your ketones. Obviously I hope that’s not the case as my heartrate monitor says I’m in the fat butning zone not aeronir or anerobic zones. I try to stay below 141 bpm. At that rate I feel like I could workout all day. I know my anaerobic rate, and I know I can’t withstand that for longer than say 45 minutes before I hit the wall. I guess I will keep logging to see a pattern.

(David Solberg) #15

Right after exercise, my glucose goes up, and ketones go down. About an hour and a half later, my ketones go high, and glucose goes back down.

(What The Fast?!) #16

I ate an early dinner tonight at 5:30pm - cauliflower crust pizza with kefir cheese (labne) and rotisserie chicken, along with a fat bomb for dessert. I closed my eating window about 6pm. At 7:15, I went a heated yoga class where I sweat out about a bucket full. It wasn’t intense in terms of heart rate, but my body temp definitely increased. I showered, came home and had a big bottle of water. I tested my ketones and BG to find 0.2 ketones and 112 BG!! I VERY rarely get over 100 BG. I have also tested BG before and after a hot bath and have found the same thing - my BG goes way up when sitting in a hot bath (much like hot yoga, apparently).

(What The Fast?!) #17

Bumping this up and adding new info.
I tested my ketones and BG this AM pre workout and 90 minutes post workout:
upon waking: BG was 82 and ketones at 0.4.
90 min after a 20 mile bike ride: BG at 109 and ketones at 0.6.

Is it normal for BG to go up so much after a workout?


On a day in late April of this year, I…

Checked my BG and BK in the morning; BG=108, BK=1.2.

In mid-afternoon, still fasted, I did 200 kettlebell swings. Five minutes after that exercise, I checked my blood again and found BG=140, BK=1.2.

I checked again an hour later (still fasted) and found BG=103, BK=0.6.

Later that day, several hours after eating, BG=104, BK=1.6.

(Marta Loftfield) #19

@KetoLikeaLady it is normal for me. This morning:

K 2.1, BG 76
3 mile hike
K1.9 BG 126

I know from experience my ketones will be up later and glucose down.
I am 60 hours into an EF. I think the glucose stored in pockets of fat is part of the rise. I’ve been told it is normal and it is a consistent pattern for me.

(Bob M) #20

I usually exercise after 36 hours of fasting. I find it depends on what state you’re in, but usually blood sugar goes up and ketones down. If I am low into ketosis (say 0.5 or lower), ketones often go up. But based on the 1,100+ samples I have, it’s not always like this. I see ketones going down or up or staying the same. For instance, I took ketones via a blood meter and ketonix (breath) before and after a workout and got basically the same (0.9 and 0.9 before and after BHB; and 63 before and 69 after).

Hmmm…it would take me a while to do data analysis on these. Also, I was wearing a continuous glucose monitor for months, and that data is stored elsewhere.