Hey! Yes, you can lose weight with Medifast. But, I think your expectations may be a little high if you think you'll lose 35-40 pounds in two months.
Rather than set a number as a goal, I'd suggest you make your goal STAYING ON THE PLAN! That will guarantee you lose weight, and you'll be much happier when the end of February rolls around, even if you don't hit some arbitrary number.
Stay with the plan! Get all the information you can from medifast1.com. Be sure to check out the condiments list, the snacks list, the vegetarian options, and so on. Be sure you measure your lean and green foods--you will probably be amazed at how much 6 ounces of chicken breast really is. But it's important that you eat as much as you are told for the lean and green. Also, drink the water you're supposed to! And don't go longer than 3 hours between meals.
The first few days can be rough, but things get much better once you get past them.
Good luck!
Jay