Energy loss? Yes. Many lifters drop the weights used a little when dieting due to either changing their overall volume or the fact that low cal/ low carb means less energy for all out workout sessions.
However, if you are noticing a huge drop in real strength, this is a sign of muscle loss.
I haven't lost strength during this drop in weight.
Chances are, the OP is either not eating enough overall, his protein intake alone is too low....or he is turned around about how to train altogether.