That is up to you, your nutrition, and how hard you continue to workout. We encourage you to continue consuming enough calories to support the new muscle mass you gained. If you do not, you will likely lose your gains because you are not giving your body the protein and calories it needs to sustain your results.
In addition, it is also very important that you continue to train hard and heavy when you're finished using Mass FX. Your body will only hold onto excess muscle IF it has a need to. So if you slack in the gym and with your nutrition following Mass FX, don't be surprised to see your gains fade.
