Firstly, the body is not a finite state machine. All the mechanisms of metabolism and there are a lot of them are, basically, active all the time. A great deal of complicated chemistry is underway, simultaneously, day and night. Including reactions whose effects cancel out, meaning that it is the balance of reactions that determines the system configuration.
(Yes! It's multivariate integral calculus, back from your youth to haunt you!)
Anyway, the second problem is that blood sugar in healthy individuals is very well regulated anyway. The blood sugar pathologies you see in obese individuals are usually pathologies of obesity, not the other way around.
The third problem is that carbohydrates, even simple ones, don't have a monopoly on short-term blood sugar effects. Insulin is usually identified as the primary regulator of blood sugar, but insulin is affected very strongly by protein as well as by carbohydrates. This is because insulin actually has a whole bunch of functions, only one of which is blood sugar regulation.
Biology is really complicated. It's the worst spaghetti code ever. It works, but there's no modularity, no information hiding, no clean APIs, everything is a global variable and there's not even the most basic concurrency controls. It's very hard to reason about.
But because it is so robust, it is easy to do thing A, get result B and attribute the results to factually incorrect theory Z9-gamma-pink-battleship.
You have an odd way of looking at things. ;) I happen to find the whole thing pretty amazing, the universe is beginning to understand itself.
Not to mention elegant in the way the human body runs perfectly on early-human food.
I'm not obese, and when eating sugar/starch I end up sleepy at times and starving a few hours later. Everyone knows it... moms have been telling us for decades if not centuries, not to give sugar to children.
Proteins/fats must be converted, meaning their glycemic index will be much lower. As such, a day or two after I substituted green-veggies & nuts for grains the difference was palpable.
I have not been stuffed or starving for over a month, lost my spare tire, and am loving it. Fits perfectly with everything I learned in chem, bio, and nutrition at uni. long before this became a movement. I don't think of this as FSM, rather differential equations such as these:
http://17calculus.com/calc08-app-ccfluids.php
There are benefits to keeping blood sugar levels stable whether people want to believe it or not.
"Six subjects were fasted overnight and were then given 40 g of triacylglycerol either orally or as an intravenous infusion over 4 h. Intracellular lipolysis (hormone-sensitive lipase action; HSL) was suppressed after both oral and intravenous fat loads (P < 0.001). Insulin, a major regulator of HSL activity, showed little change after either oral or intravenous fat load, suggesting that suppression of HSL action occurred independently of insulin."