@EmilyC, when do you exercise? After meals, before meals, evening, morning, etc?
And can you tell me a little bit about your exercise? Like what type it is and how hard it is? And how frequently are you exercising?
The body uses numerous fueling systems. These are not a “one-or-the-other”, or an on/off scenario. They overlap and compliment each other.
Your muscles store carbs for use - called muscle glycogen. But one thing about keto is that you do not have the same level of glucose available for fuel, and it takes your body longer to replace the muscle glycogen.
Your body can create glucose from non-glucose sources. That is called gluconeogenesis. But it takes a lot longer for your body to create glucose from non-carb sources than it takes for it to just use glucose!
Ultimately, for low carb and exercise, you would want to have a sufficient zero basal before the exercise (if you are on a pump and can turn it off). And also you should exercise later in the day after you’ve had a chance to have a little bit of your food converted. In the morning before breakfast your tank is empty.
Also, exercising every day on keto is harder, because your body is not able to replace glycogen as quickly on a low carb diet. If you are exercising every few days instead of daily, at least this gives your body a chance to replenish. But if you keep dipping into the well daily, your body is always playing catch-up.
A lower intensity exercise is easier to manage, because it can use fat metabolism for fuel a lot easier than a higher intensity exercise. There is a point in exercise where the intensity is hard enough that you just can’t do it without enough glucose. And your body will do all it can to pull whatever glucose it can. You are seeing this with your BG drops!
Another thing that can help is a slower warm-up. For example, if you immediately get into your exercise, your body is going to try and use the quickest fuel source it can. And the quickest fuel source to use immediately is glucose. If you have a slower warmup, your body can use fat metabolism and then that process can be sustained a little bit longer into the actual exercise.
These are just a few thoughts, but feel free to ask specifics.