Exercise in the morning and higher blood sugar

(Bob M) #1

So, I exercise in the morning, usually from 6am-7am for 1/2 body weight training (1/2 body per session), 2 days/week; 5:30am-7am for a full body weight training, 1 day/week; and two jogging sessions per week of about 35-40 minutes, currently starting about 6:30am because I need it to be light out to take my dog with me. 5 days a week.

I exercise after having coffee with a small amount of cream. No food whatsoever.

Here are some blood sugar examples using a Keto Mojo (yes, pin prick, yes a lot of possible error): (BW = body weight training):

Before short BW: 110; After BW: 120
Before jogging: 115; After jogging: 121
Before long BW: 121; after long BW: 129

NOTE: A similar pattern of rising blood sugar exists for me, even when I don’t exercise. I don’t think it’s as pronounced, though.

  1. Anyway, from where does the blood sugar come? I’m assuming from the liver, but how?

  2. Why does the body give me higher blood sugar?

(Peter - Don't Fear the Fat ) #2

I really don’t get it. I’m looking forward to the answer because logic tells me if you use energy the BS should go down.
This seems back to front! … I assume you think the same. Are you a fusion engine?

(Chuck) #3

When I get up my BP is the highest of the day, and after I do my walking, or exercise bike, or resistance training my BP is much lower. I would think that blood sugar would do the .

(Joey) #4

For starters, the variability you’re citing is well within any consumer-grade glucose monitor’s accuracy rating. So these are not statistically meaningful differences.

Having said that, pretending they are meaningful, yes, in your situation (fasted, minimal carb WOE) your body releases glucose stores on demand - and the interaction between what’s then in your bloodstream and insulin levels and insulin uptake by muscle (and other) tissues all conspire to produce what you are measuring in your bloodstream at that moment.

I don’t see anything mysterious in these figures. My own glucose can rise or fall depending on just how strenuous the exercise is that’s invoking the demand … aerobic exercise produces a different response than strength training, sleep, stress, fitness, all affect such things as glucose/insulin circulation at any particular moment.

You’re clearly doing awesome with these workouts. Let your blood glucose do its thing! :vulcan_salute:


Others smarter than me can expand on this point scientifically, but the answer lies in the release of adrenaline when engaging in physical activity.

As to the question of “why” our body works that way, here’s my completely unscientific theory/belief: when “exercising” to hunt game, wooly mammoths, forage, etc. in our primal days, the body learned to release adrenaline to assist with the endeavor and give us the motivation/spurts needed to succeed in our efforts. In turn, this likewise signaled the liver to pump more glucose to aid in the effort and to ensure we had enough energy to prevent us from “bonking” out while our spear was raised. So, in a nutshell, survive-and-thrive mechanism.

(KM) #6

In other words, morning physiology has reported to the brain that we have no food, and our metabolism is enthusiastic about the idea that we get off our butts and get some, so it’s providing us with all the energy it can come up with.

Bob, if you wait another half hour while sitting down and check your blood glucose again, has it dropped down in response to the disappointing news that you have apparently not succeeded in capturing any wooly mammoths?

(David Cooke) #7

There must be a load of different hormones that are stimulated when you start a workout, I know that heart rate is partly activated by a hormone that is released and of course the action of this hormone doesn’t stop immediately just because you sit down. If you follow my abstruse reasoning, your body demands glucose and that demand won’t stop in a hurry. I never measure heart rate, blood pressure or glucose after my morning runs.

(Joey) #8

= dawn effect.

Otherwise, we’d sleep away most of the day until the pizza guy showed up.

(Robin) #9

I miss the pizza guy

(Rossi Luo) #10
  1. The cream might contribute part of your blood sugar, the other part I don’t know, from the liver or whatever cells. I have dawn phenomenon too, my blood sugar is always around 5.9 even I was 0 carbs the previous days.

  2. I guess it’s simply because your body doesn’t know how much blood sugar you actually need, so it just produces more than you need, the body is not a computer, it’s not good to do computations and predictions :grin:


This is a good and interesting point. We are wired not to die. Our default body mechanisms are designed to and operate to prevent us from dying. So by spurting glucose for the dawn effect, the body does so because it doesn’t know if we’re going to roll out of bed and go make a cup of coffee or go chase that small game that we heard rustling outside the cave. Chasing game upon waking without adequate glucose runs the risk of passing out and knocking your noggin on a rock

(Bob M) #12

Just for more info, I have years of this data. I know the numbers aren’t that accurate (I don’t trust these pin prick monitors at all), but in the time I’ve been tracking, there’s only been a single time when my blood sugar went down in response to exercise. And I think that was just the plus/minus 15% of the meter.

Back when I had a CGM, this is what it looked like:

What I noticed was higher overall blood sugar (as per the value on the right) any day that I exercised, and lower on days I did not. I have page after page of data (at home) that look like this.

@kib1 After exercise, I shower, take the dog out, crate the dog, drive to work. I then forget to take blood sugar. It’s also a complex calculation, because my blood sugar goes down all day from about 11 am. And eating a keto meal often causes my blood sugar zero rise or even a decrease. As you can see from the above, I ate sometime around 10 am, but there’s no way for you or me to know that just by looking at the curve. I know it because I get hungry a few hours after exercising and eat then. (Yes, I don’t eat anything for several hours after exercising.)

As for many of the other comments (was going to tag everyone, but I am at work and actually can only take a few minutes here), dawn effect definitely happens to me, but this goes beyond that. See here:

Tuesday 9 April is what I show separately above. Monday and Wednesday, I did not work out, and my overall blood sugar goes down those days.

It’s just now that I’m working out 5 days a week (probably only 3 days a week for those April graphs, which were years ago), and my blood sugar is higher all the time now. I’m imagining the curve from 9 April, but 5 days a week instead of 3. That only gives me 2 days/week of lower blood sugar. My HbA1c has crept up to 5.2 from 4.9.

I have more muscle mass than I did a few years ago, maybe that factors into it too?

I still fit into all my 34 pants and tried on an old suit. While I can fit into it, it’s tight, but that’s because of muscle mass. For instance, my thighs completely fill up the pants, and jacket is tight mainly at my chest.

So, I assume there’s some “feedback” mechanism telling my body to pump out more blood sugar, but I’d like to know why. Glycogen replacement? Red blood cells need more sugar? More important, is my Hb1c going to continue going up, and if so, why?

And I should note that on most of the days I do body weight training, I eat about 50g of carbs. (That’s now, not when those graphs above were taken.) I’d LOVE to have a CGM to compare what happens if I eat 50g of carbs one day after a workout and another day with no carbs after a workout. It’s possible to do this with a pin-prick meter, but my blood sugar goes up and down within an hour after eating. I’d need to take blood sugar every 15 minutes or so, which is quite painful.

I thought that if those carbs go to my muscles that morning and daily blood sugar would go down, but that doesn’t appear to be happening.

(KM) #14

That is an interesting pattern. I assume that releasing glycogen is the equivalent of ingesting glucose in terms of the glucose reported in the blood … I have heard that metabolism can be raised for many hours after a workout … maybe this “raised metabolism” is a steady release of glycogen all day? Have to admit I don’t have a great theory about this!

(Bacon enough and time) #15

“Raised metabolism” refers to a faster metabolic rate, not to the level of serum glucose. Glucose rises during exercise, in order to fuel explosive power. But fatty acids fuel endurance, when available.

Of course, people who aren’t eating enough fat to supply their body’s energy needs are probably going to be making glucose for that purpose, but I’d be wary of losing muscle mass, that way.

(Alec) #16

Here’s my take. Standard BG levels that the medical community tell us are “normal” are derived from studies of people eating a normal SAD diet. They may or may not be best or normal for those of us on an extremely low carb diet where the liver is making the required glucose on demand.

What I have learnt over the past 20 months on being a carnivore is to trust that my body knows exactly what it is doing, it knows MUCH better than me what to do and how to operate, and if it wants a certain level of BG, it will make it and use it and store it as appropriate.

My philosophy on carnivore now is to eat as low inflammatory diet as possible (which to me means carnivore) and get out of the way of my body doing what it does best. Us thinking we know better than our bodies is arrogance of the highest order.

(Bacon enough and time) #17

Hear, hear! :+1:

(Rossi Luo) #18

I’m curious that if you change your morning exercise to some other time (e.g. evening or afternoon), and do it for 2 weeks, what the curve will be, 2 peak?
My guess is that, at the first 2 or 3 days, your BG would not rise after your exercise, because your body is not used to making glucose at that time, perhaps your body cells are waiting for the next diner at that time.
But after 3 day,s your body cells might learn that “Oh Jesus, this man always ask us to work at this time, come on brother”, and they may adapt to your new behavior?
If this experiment can be true, then we can assert that someone’s body cells can adapt metabolism after days of learning.


Don’t forget working out is a stress to the body, which can raise it. If your workouts are intense enough that you’re going into a glycolitic range, your body will make more glucose to fuel it. Fat isn’t a fast fuel. Either was those differences are completely ignoreable amounts as far as you needing to worry about it, assuming your’e not though.

Also remember that earlier AM workouts (most of mine start around 0400 or so, even though I’m pretty awake, my body isn’t. Which means even more of a stress to work it vs later in the day when you’re all broken in and physically warmed up.