I think that is based on how much one has to lose.

Rule of thumb is 10 percent in the first two weeks then 5 percent a month.

Of course it really depends on age, and past dieting habits. I know it is useful and interesting information to find out how everyone else has done.... But don't get too caught up on comparing your rate of loss to others. I personally lost 35 pounds in two months. Then didn't lose a single pound for 8 months, which I attributed to my body playing catch up.

If you happen to lose at a slower rate than say someone else then you begin to think you are doing something wrong or the diet isn't working. Which neither could apply at all.