What I've read is that chronically lowering your calories sends signals to your body that there isn't much food around, or at least not as much as what's been around up till that point. The body then slows your metabolism down, you simply expend less energy doing your normal activities. If your body didn't do this and you kept burning the exact same amount of calories it did up till the point when the caloric intake dropped you'd slowly disappear, right?;)
This is all a matter of degree of course. A bit of CR wil indeed make you lose weight as you are experiencing. The issue comes in determining that point where the returns bece diminishing, the point at which your body just slows down. At that point then it'll be even harder to purposely burn more calories through activity. Because your system is running in a lower gear if you will.
As many will no doubt tell you, while knowing your caloric intake is wise, perhaps a better way to lose unwanted weight is to engage in strenuous activity that will have positive effects on your hormones. This is usually said to ramp up fat burning, use the calories you do eat in a better way (repair, rebuilding, refueling for more activity, etc).
Lifting things heavier than you've lifted up until now is a great way for women and men to set their hormones rocking, fat burning, muscles rebuilding etc. The single best way to get some degree of body recomp.
All other things being equal though, if you are fit and healthy and exercising well regularly, CR will indeed make you lose some weight, you just want to make sure it's body fat and not muscle.