Eight pounds in the first week? Clearly that is not fat loss when you consider that that amounts to 4000 kcal of fat per day. So it is something else -- the something else is water that is shed as the body transitions from burning glucose to burning ketones, which requires a different electrolyte balance.

It is not at all uncommon for the body to overshoot in doing this and to have to reclaim some water at the end, hence you might see a weight gain or a protracted plateau shortly after the big initial loss. If you understand what is going on, it makes it easier to accept and work through, but I don't think anyone ever actually is at peace with it -- it's just damn frustrating.

As you go forward (and you might recall this from your first go, though different people are different and some don't follow this pattern) but you will probably go for extended periods of time (measured in weeks) of not losing any weight or even gaining some followed by a short bout of losing several pounds in just a few days (known as a whoosh). This is due to the body holding back water to keep the fat cells at their full volume, expecting the fat to be replenished once the short-term famine is over, and then deciding that it is time to let things go. In my case the normal pattern is that I stay the same for about two weeks and then dump five pounds in a couple days. Wash, rinse, repeat.