Update

YESTERDAY

So yesterday I had no food and went to the park with my older sister and mother, my sister and I walked at about 3.5 MPH for about 90 minutes (the entire walk) we walked about 2 to 3 miles.

The entirety of the walk added up to be -395 calories.

calorie net for yesterday: 1200 - 0 intake + -395 calories = (-1595 calories)

_______________________________________________________ 

TODAY

I had popcorn in which is 94% fat free, 30 calories per bag (15 for 1/2) with 27g of carbs. It is thought that there are 4 calories per gram of carbohydrates so 4 * 27 = 108, and that leaves me with 138 calories to burn for the day so I will have burned off all the carbs and the calories. 

TIP: If it is "fat free" it will be extra high in either calories or carbohydrates.

Today's calorie net: 1200 - 0 intake + -138 = (-1338)

Because a child's body needs 1200 calories a day (a healthy woman needing 1500, a healthy man needing 2000) every day you fast you are in the deficit of that amount (in this case 1200) of calories. 

Basically it is:

Scenario 1

You eat your 1200 calories and burn them all off, you are not gaining or losing but simply maintaining.

Scenario 2

You don't eat 1200 calories and burn of XXX calories you are losing.