Try adding in a EAS Carb AdvantEDGE shake within 30 minutes post workout. I am not on Medifast, but on a program very similar to it and see a doc quite regularly in regards to it. Also, drop your exercise down to no more than 45 minutes of strenous activity (you can walk to your heart's desire.) That is what was recommended to me and it pushed me out of a six week long plateau. You may also want to check to see if you are not already on it, of maybe getting on board with the 4 & 2
plan as oppossed to the 5 & 1 plan since your activity level is so high.
FWIW, this is Medifast's recommendations
on exercise while on program.
If you do not currently have one, get an account on either MyFitnessPal or LoseIT! to track your calories (yes, even those from packages....it will help you later when you go to maintanence) and your exercise. It will advise if you are "eating your calories" as my doctor put it. It helps when you see the numbers. It really does.
Also, keep in mind that a plateau is generally classified as WEEKS (we are talking SEVERAL) of none movement, not just one or two
Look at inches in addition to pounds. Our bodies are great at adapting, but sometimes, it can only do one thing at a time.