i'm 5'5", and I used to be a 12 (sometimes 10) at about 140 lbs before I gained the weight. I got up to a size 18W (ok, 20 in denial) at my top weight of 210, but had gotten back down to a tight 16 when I started Atkins at 186. The first 25 pounds took me two (really, two and a half) sizes to a size 12 at 160. After losing 10 more pounds, I was a pretty comfortable 10 at 150, but there was a little less than 10 lbs between a size 10 and an 8, since 8s were getting a little loose on me at 140. There was only a 5-lb difference between an 8 and a 6, which I got into at 137, and 5 more lbs to a size 4, which was about 132. Now I'm 128-129, and some 4s are even a little loose in places -- two or three more pounds might occasionally take me into a 2, although I'm close to the limits of what my frame will permit. So for me, there was about a 10-lb difference between each size until I started to get really small, and then it was more like 5 lbs. Each pound lost really does make a difference now, as does each pound gained -- my clothes are noticeably tighter if I'm retaining a couple pounds of water.