
(I just thought of this too, and it is the case in my case) You may be gaining muscle mass. Instead of
losing weight, you are staying the same by developing muscle mass. (I actually began to gain weight because of my training routine. I was training like a body builder which is really all I knew. Now I concentrate on cardio, cardio, cardio! The treadmill, the stationary bike, the eliptical machine and the stair stepper are my best friends in the gym.