training plateau

Im just starting back up from being out of the gym for about 2 years. I completely let myself go. Ive been back in the gym for about 3 months. Im slowly losing weight and each workout im getting stronger. Because of this im not changing anything in my diet or workout routine. At some point im expecting the strength increases to stop. what im wondering is what would you guys consider a plateau that would require you to change something, either diet or training. A couple weeks of no progress? A month?

a true plateau is when body weight fluctuations hault (wither your trying to gain weight or lose weight, it comes to a stop), body composition comes to a hault , and not only does your strength in the gym stop but it may actually regress.
also, sometimes things like getting a pump in the gym becomes more difficult to achieve.

note - things like strength increases are not always just how much weight is on the bar.. things like total reps, sets etc. are a gauge of progress being made. if you were benching 225 to total failure at 12 reps, and the next week you squeeze out 13 , then your progressing and not at a plateau.. also if your able to add volume, like one more set of an exercise with the same amount of weight and reps , then your progressing and getting stronger/fitter.

I currently measure my workouts by load (repsXweightXsets) so if I go up weight I can track a little closer if im actually lifting more when the reps drop initially. So in this case, if my total load stopped increasing but my body fat was dropping would you consider this time to switch things up, or just keep thinks the same and enjoy the fat loss.

If I hit a wall I will often just change routines for awhile. I'm going through the same thing right now.
Today I trained at a different gym and did a whole new workout.