I think (and since I've only been on it for a week, I can only base this on what others have said) it depends a lot on your eating and exercise habits. If you currently eat lots of sweets and high-fat snacks and continue to do so (even if you only cut back because you're fuller faster) your weight loss will probably take longer. If your primary source of exercise is walking from the living room to the kitchen, your weight loss will probably take longer.
Like Mindalynn said, lighter people will lose weight slower, and likely in smaller increments. I believe I read somewhere that said a loss of about 1% a week (of your current weight) was pretty typical (when combined with changing your eating/exercise habits). So, if that's the case, the first week you *could* lose 1.45 lbs; the second week, 1.43 lbs, and so on.