Going to keep this as slim as possible since I already wrote a novel:

It's not about refined vs unrefined sugars. In the blood, all carbohydrates break down to simple glucose. Refined sugars just do that faster.

Net carbs being as low as possible matters. Simple formula is carbohydrates minus fiber as we cannot properly break down and digest fiber (mostly).

If you consume too many carbs, your body releases insulin. Insulin's function is to carry important nutrients and energies to fat cells/muscles.

To enter ketosis, you cannot have an insulin release. Insulin kicks you out of ketosis.

When under ketosis, ketones essentially perform the function of insulin, but you are burning fat instead of efficiently delivering carbohydrates and calories to fat cells. Your body synthesizes important glucose that your brain requires from gluconeogenesis, which is synthesizing glucose from protein.

Even on a confident 0g net carb keto diet, it's still important to monitor your macros because too much protein can cause too much glucose to be synthesized which will cause an insulin release and kick you out of ketosis.

Ketosis takes time for your body to adapt itself into, and absolutely no time at all to shrug off.

Obligatory side note: If you are prediabetic or diabetic, consult with a reputable physician before going into ketosis, as some are confident that this can cause keto acidosis, which is an entirely different condition.

Fun fact though: Diabetics have become asymptomatic when under ketosis. Turns out that prescribing all these medications and telling the patient to eat a candy bar may not be the best way to solve diabetic symptoms. Go figure.