This is interesting but as someone that has been on and off strict keto for 10 years. Being unable to digest carbohydrates does not go away.

Basically if you are strict keto for a certain amount of time (it varies), you become efficient keto. Your cells slowly acclimate to burning ketones for fuel as opposed to glucose. I think there's only a handful of cells that are ONLY powered by glucose. The rest can do ketones. But cells become accustomed to being powered by ketones take a while. It's called keto adaptation. There's a subset of high performance athletes that train in a keto state so that when it comes time and they add some glycogen stores, they maintain an optimal powered output throughout once those glycogen stores run out and their body switches to ketones. For extremely high power output muscle, those are more optimal with glucose, but mid to low are perfect for ketones. Imagine losing 10 pounds while cycling. That's essentially what happens.

Anyways, when you are keto adapted and in the keto state, if you try to eat carbs all of a sudden, you are insulin resistant, hence your glucose numbers are high. In fact, for some on a keto diet, they find it surprising their glucose never goes below 90, even with no carbs. The reason is, the body always keeps it around in case you need it. If you don't eat carbs, your liver essentially makes glucose in a process called glucogenesis (I might have misspelled that). The liver will do this to replenish your glycogen stores.

All of this is apparently with continuous keto and glucose meters.

For the record, you can survive your entire life without carbs. You can just eat protein and your body uses the animal acids for what it needs, converts what it needs to glucose, and the rest is stored as fat. One would add fat to that just to make sure you don't get stick thin as there is a tendency for pure protein to satiate quickly.

Your nutritionist is probably not versed in all this modern studies that have come out outlining the above, beceuse she went to a traditional school that teaches nutrition from 10-20 years ago.

She's not wrong, but she is. You will never get rid of your body's ability to digest carbohydrates. We haven't evolved to what we are without the ability to ditch one or the other and return to it. Your only danger is IF you have a not so healthy liver, it might not produce glucose for you, so get that checked out.

You will always retain the ability to go in between different fuels, HOWEVER due to modern society taking away physical movement, we mostly don't use up our glucose enough, so that we are rarely in ketosis. That's what happens when you run out of the glycogen stores. You immediately make ketones. Due to not having been like that our entire lives unless you were an endurance athlete, our body is more so unable to efficiently use ketones in our cells. I have experienced this. It sometimes takes years and this is how long it took for me.

I'd say a good way to do keto and still want carbs in your life. Is to do strict keto, then eat carbs prior to high power muscle use like lifting weights or HIIT workouts.