I don't think you can draw any conclusion from weighing 2 days in. If you lost much it's probably mostly whatever you ate the days before that was still making its journey through your metabolic system and water.

Even though you only drink water during the fast you do suffer from some osmosis because you additionally slowly deplete yourself of minerals that get excreted through urine.

If you do a one week fast you will lose weight, there is simply not enough glucose floating around for that time so you must rely on body fat to provide you with necessary energy.

If you want to know how much weight you lost it's better to weigh 2-3 days after you stopped the fast to get a good idea. 

 thanks jeroen. I guess i was more curious on the differences of body mass, muscle vs fat and metabolic rate. I have higher metabolic rate, low bone density and higher fats. My sister on the hand has more muscle and low fats, lower metabolic rate, high bone density,  and often has different reaction. Jack i guess has high bone density, lean with barely much fats and high metabolic rate hence curious on the different outcomes. Some of us here do the sea salt + distilled water so i don't know how the mineral loss impacts the body during fasting as I have never measured it.