Heya Stalefish
You'll notice it when your doing your normal workout &
diet and you wont be losing the weight or gaining muscle. If you change your workouts up you will never hit a plateau, just add some variety or if your using a preprogrammed
cardio machine theres lots of different programs.
If your doing something right now and its kind of easy for you then you should increase your intensity, personally I think everytime you workout you should push yourself just a little more each time, maybe 2 more reps for
weights or 2 more minutes on a
treadmill /
elliptical trainer really adds up in the end.