Will dextrose break a fastt?


I like to take preworkout while fasting, but i’m not sure which of the ingredients in the PWO will break a fast. will dextrose break a fast?

(Allie) #2

It’s sugar so not a good idea on keto even when not fasting. Why do you think you need it?


it’s an ingredient in my preworkout which includes caffieine+citrulline+theanine

(Donna ) #4

Dextrose would break a fast, sorry.

(Allie) #5

I guessed that but was asking why you think you need a pre workout? I’ve never had the need since being keto.


yea i just found out here :frowning:

(David Pinkus) #7

I was curious the same thing and from an IF perspective heard a lot of contradictory advice, with too many opinions and no data/citations.

So I wore a Continuous Glucose Monitor for several weeks, tested lots of food combinations, and saw no discernible difference in my blood glucose levels when I worked out with a pre-workout drink or without (but I also drank it as I started to warm up and already increased my metabolic rate). My glucose always went up while I worked out, with some variation based on the actual exercises those days, but always returned predictably after my workouts to the same fasting levels. Now that’s not insulin, as there is not yet an affordable consumer test option for that. And my DNA and gut-biome are different than yours, so your mileage may vary. But based on my glucose curves, and the tracked weight differences day-by-day, it didn’t make a difference.

The following is my opinion, so you should test for yourself, but I have not found a dramatic on/off fasting state difference when my body is demanding high levels of glucose through intense exercise (as measured by my GCM) and the minimal caloric/carb consumption that would be contributing a negligible amount to it.

That being said, there is scientific, peer-reviewed data (easily Googled) that some artificial sweeteners cause an insulin response, with no caloric benefit, which actually contributes to insulin resistance. So be careful which sweeteners, and how close to exercise, you consume them. It may be better (test and research, don’t listen to me) to consume a trace amount of actual digestible caloric sweetener, as long as your body’s immediate energy demand far exceeds what your giving it.

As far as GCM, I got the FreeStyle Libre System. A 2-week sensor was around $35, so I did it for a month. I used my iPhone as the reader (and didn’t buy their reader). You’ll need a script. It was by far the most important thing I did to understand my levels, and how which specific foods and fasting affected me and for how long. It should be the first step in any fasting regiment (which again is my opinion, so treat it as such) :slight_smile: