So, even a rather overweight person can only lose a pound or 2 of fat a week?
My earlier comments might have been a little conservative... most people say 2-3 lbs per week is about the upper limit of what's safe. I've personally averaged about 3 lbs a week for the past 6 weeks, so I know from personal experience that 3 lbs / week can be done. But it's not easy... 3lbs might not sound like much, but to lose that much weight in one week takes a lot of f'in work.
One time before I managed to average between 3.5 - 4.0 lbs per week for about 4 weeks, and at the end of it I felt like total shit and was weak as hell. So in my mind, I feel like about 3lbs is a reasonable number to consider the upper range of what one can reasonable lose in a week.
Not to suggest that I'm necessarily a representative sample for everybody, but my experience matches the numbers thrown around the the "authorities" on the subject, FWIW. Individual results may vary, of course...