Happens to me every month, about twice a month now that I've been losing for a while and now that my monthly cycle is normal.
I'll stay within a two pound range for the week or so during ovulation and the week of my period. The off weeks usually see a drop on the scale daily.
My thought on this is that I'm steadily burning fat the whole time since I'm in a calorie deficit. But since I'm at the point where I can only reasonably expect to lose 1-1.5 lbs per week, that loss can easily be masked by a couple pounds of fluid retention due to hormones.
The hormones peak, I drop the fluid I've been holding, and voila: 3-4 pound whoosh. Same thing happens when I exercise hard enough to get muscle soreness.
I get frustrated with it sometimes too, but it doesn't bother me as much now that I'm used to it and I can actually predict when it's going to happen.
Just keep telling yourself that if you're at a calorie deficit, sooner or later the scale is going to have to show it. Hang in there!
