Yes, it's mostly water weight. All carbohydrates make the body retain water, and when you restrict them, water (urine) is released big time. I peed like crazy the 2nd and 3rd day on the program.I expect a loss of 1 to 2 pounds per week from here on out.
Ho Hum wrote:
If you lost 4 pounds in 5 days, odds are you messed up measuring somewhere along the line. Do the math on the calorie deficit required to lose 4 pounds of fat: 14000 calories, over 5 days = -2800 calories/day = you were insanely active while eating very little. Which would mean that you didn't just sub out wheat, but went on some kind of extended fast.
More likely you just lost some water weight and took a dump somewhere along the line.