Hi Sue and welcome to the forum,
One of the great things about Medifast is that you dont have to design your own menu and calculate everything. Just follow the easy plan that's been developed, tested and proven by professionals for years and you're on your way. There's no worry about making mistakes about which foods you're adding or that temptation to "fudge" and think just a little bite of this or that won't be bad.
The 1st 3-4 days can be a little hard, but once you get into the mild state of ketosis, you'll find that hunger isn't a problem. Try to get busy at something to take your mind off things, and before you know it, you'll be through the first few days.
It's VERY important not to skip a meal and be sure you're getting all your water. Missing a meal can actually slow your weight loss.
Many people find that the first few weeks you can lose nearly a pound a day, but dont be discouraged if you don't see these kinds of results. Just remember that if you follow the program, you will succeed.
In a Johns Hopkins study, the "average" weight loss for women in a 16 week study was 47 pounds. Now that's "average". Not like some other diets that make outrageous claims but add the disclaimer (results not typical), this was a clinical study done by one of the most prestigious Hospitals in the country. That means if you're average and stick to the plan, by springtime you can be around 50 pounds lighter. By next summer you can be shopping for that new swimsuit....
All the best,
Unca