LACEY ~ I have been here a while, and I have heard people say this again & again. While we may not know the exact reason this is happening, we do know that it IS happening. I have seen this in myself as well; so I have been doing calorie cycling -- moving my calories up & down (1800;1600;1700;1900;1600;1800, and so on).
BTW, I was eating fewer calories at one point 1500-1600 and hit plateaus there too; that's when I started the cycling (upwards). I will try whatever works; and have advised others to try various tactics too (increase cals or decrease them; increase exercise, and yes, even decrease in a few cases).
I know that I am getting smaller ~ my clothes are getting looser and I can see my face is thinner, and others have commented on that (and my skinny fingers: my wedding band no longer fits). Only time will tell, how it goes; and I'm tracking carefully.
I suspect that after years of yo-yo dieting, my body is fighting me just a bit -- possibly for self-preservation. It may not see less food as a good thing like we do; I think my body may be over-efficient now, so I have to try to fool it. And, I am trying to finds ways to increase my metabolism & my energy "output" to see if that helps too (with some physical challenges, I have to be more creative).
Of course, this is just my own personal theory; I have no other proof except that I am losing weight again -- and I refuse to give up ...