LC and how your body works

Rianne said:

Hi Maryrachel,

I'd like to share my experencience and love to further follow yours, because I recognize your story. I've started low carb about 5 weeks ago. So far I eat approx. 25 grams of net carbs and that mostly is under 50 grams of total carbs. I have similar experiences with my basal insulin/bg's. Before lowering the carbs, I used to have to lower my basal insulin 2 hours in advance of physical activity. For brisk walking for lets say 2 hours or more, I lowered it to 10%. For housecleaning or gardening, I lowered it to 50%. I still have not found the correct levels for my new diet yet, but I do experience that I need to lower basal much less. I seems to come closer to 40 or 50% for brisk walking and 70 or 80% for the other activities. I have been thinking that, when I used higher boluses before meals, the boluses would still pretty much effect the lowering of bg because of physical activities. With no or much lower boluses for meals, maybe the real effect of the acitivites on basal level appears.
My writing of course is not an anwer to your question, but I hope the recognition supports you a bit.
Good luck!

Greetings,
Rianne

Click to expand...

ziggy_w said:

Hi @maryrachel,

I am not a T1, so can't comment on the insulin.

However, I might be able to help with your other question -- just happen to have googled it a few hours earlier.

The reason that your blood sugars might not have dropped dramatically during your rigorous walk might be adaptive glucose sparing. This means that on a ketogenic or low carb diet, your muscles prefer to use fat over glucose in order to spare glucose for essential processes such as creating red blood cells or for the brain.

Here is an excellent explanation, I read on one of the sites I found:

Why would your peripheral tissues be primed and adpated to remove glucose from blood if… there isn’t any glucose in there to speak of? No, those tissues adapt. Glucose transporters fold back inside the cell from the surface, instead the cell becomes more adept at taking in fat which is circulating. You literally become adapted to sparing glucose for use by those cells which absolutely require it. Some brain cells, red blood cells and testes require glucose because they do not have mitochondria!
​

Then again, as @helensaramay says it might be related to insulin -- not really sure as I am T2.

Click to expand...

tim2000s said:

@maryrachel it's a fairly straightforward process that goes on, but there's a clear difference between "Low carb" and "Very Low Carb".

In the former, you're tending to eat smaller amounts of carbs (usually no more than about 80g per day), so the amount of bolus insulin you need per meal drops. Typically, basal doesn't change that much.

It's worth bearing in mind that injected insulin in the body has a half life of around 57 minutes, so if you eat regular amounts of carbs, so for example, a meal containing 70g that requires 7 units of insulin, 3 hours after eating your still have around 1.75units of insulin still on board. We know that in a normal metabolic state, aerobic exercise and activity (walking, moderate running, etc) causes our muscles to consume glucose more effectively by activating specific transporters. These are the same as those activated by insulin, so having both the exercise and the remainder of a bolus on board causes the muscles to consume additional glucose and drop blood glucose levels, which is why we usually lower basals before exercising, in order to reduce the effects of insulin in activating those transporters.

If you are eating fewer carbs, then your active insulin after three hours is much lower (based on our previous calculation, 25g carbs = 2.5u, which leads to 0.65u available at 3 hours, or roughly a third) meaning that you don't find that it is activating as many glucose transporters, or in other words, @helensaramay is correct.

When very low carb, i.e. below the ketogenic threshold, where your body has converted to using fats as the primary energy source, then the body actively reduces its sensitivity to glucose and reduces the number of available glucose transporters in order to burn fat in preference to carbs, as per the quote from @ziggy_w, so you are operating in a different metabolic state.

Given that you've only been lower carb for a few days, and that you are not at a carb level that is normally ketogenic for the vast majority of the population, the likelihood is that it is the first mechanism that is having an effect.

Click to expand...

tim2000s said:

@maryrachel it's a fairly straightforward process that goes on, but there's a clear difference between "Low carb" and "Very Low Carb".

In the former, you're tending to eat smaller amounts of carbs (usually no more than about 80g per day), so the amount of bolus insulin you need per meal drops. Typically, basal doesn't change that much.

It's worth bearing in mind that injected insulin in the body has a half life of around 57 minutes, so if you eat regular amounts of carbs, so for example, a meal containing 70g that requires 7 units of insulin, 3 hours after eating your still have around 1.75units of insulin still on board. We know that in a normal metabolic state, aerobic exercise and activity (walking, moderate running, etc) causes our muscles to consume glucose more effectively by activating specific transporters. These are the same as those activated by insulin, so having both the exercise and the remainder of a bolus on board causes the muscles to consume additional glucose and drop blood glucose levels, which is why we usually lower basals before exercising, in order to reduce the effects of insulin in activating those transporters.

If you are eating fewer carbs, then your active insulin after three hours is much lower (based on our previous calculation, 25g carbs = 2.5u, which leads to 0.65u available at 3 hours, or roughly a third) meaning that you don't find that it is activating as many glucose transporters, or in other words, @helensaramay is correct.

When very low carb, i.e. below the ketogenic threshold, where your body has converted to using fats as the primary energy source, then the body actively reduces its sensitivity to glucose and reduces the number of available glucose transporters in order to burn fat in preference to carbs, as per the quote from @ziggy_w, so you are operating in a different metabolic state.

Given that you've only been lower carb for a few days, and that you are not at a carb level that is normally ketogenic for the vast majority of the population, the likelihood is that it is the first mechanism that is having an effect.

Click to expand...