Secondly, losing weight too quickly when you don't have a significant amount of weight to lose can result in muscle loss as well as fat loss, which can decrease your metabolism and make it more difficult to maintain your weight loss.

CNN: Is it possible to lose 15 pounds in one month?

It is difficult to "troubleshoot" your weight loss efforts without more information, but your struggle brings up a couple of important points.

CNN: I'm exercising; why can't I lose weight?