What is the effect of fasting on carbohydrates?

Fasting is not eating.  What do you mean by "fasting on carbohydrates" ? 

It allows your body to burn glycogen that has been stored in the cells from prior unused blood sugar which is the result of the metabolic process of converting carbohydrates and is absorbed through the digestive system into the bloodstream and then stored by means of the hormone insulin which is produced by the pancreas. The glycogen causes the fat cells in the body to expand which makes a person gain weight and eventually appear "fat". Consequently, when a person loses weight they are really just burning that stored glycogen, not actually losing any fat cells. 

Nothing much. While fasting is good for us, it doesn't necessarily cause fat loss, unless it's practiced long-term. You can research this online.

It’s not really good to not eat carbs, your body needs carbs (complex carbs) from like oats, whole grains, quinoa stuff like that. If ur looking to lose weight you totally can by eating carbs. I eat about 120 grams and still lose weight! Just make sure your in a calorie deficit, that’s all that matters! And also eat protein, it keeps you full!