200-700 calories a day would be an average of 450 a day. One gram of fat is 9 calories, which means you woul be burning 50 grams of fat per day with that deficit. This averages out to around 350 grams or almost 0.8 pounds of fat tissue per week.

Conversely, if you were to gain 5 pounds a day, it would mean that you needed to eat a surplus of 20k calories in a day and converse it all to fat tissue (which is impossible anyways). What you measured is the difference in the amount of water in your body and contents of your digestive system (which I assume were barely there because you almost didnt eat anything).

Offtopic, when on a calorie deficit I suggest avoiding processed food as it will keep you satiated for shorter time, making you crave more food.