7 kilos - wow!
I notice an aftertaste with a few products, but not many. I'm not a very picky eater, though - probably why I got so fat - it all tastes good to me.
But I know other people have complained about it. As for the coated tongue - that's new to me, too. Do they sell tongue scrapers in pharmacies there? Over here they're sold with the toothbrushes - they're supposed to help with bad breath.
Water is very important! Personally, the Medifast food makes me thirsty. I have no trouble drinking 3 liters of water a day (I count my coffee and tea as water). You need to flush out the waste products your body creates by burning fat.
Don't exercise yet if you're not up to it. Here the Medifast people specifically say to NOT exercise in the beginning of the diet. I waited 8 months and 70 pounds before I felt ready to start an exercise habit. Now I can do a 90 minute hot yoga class, run 5k, go 50 minutes on an elliptical machine, and weight train for an hour with a trainer. And I do all of it regularly.
And last - EAT ALL YOUR MEALS! This is such a low calorie diet, you can't afford to skip any meals. Why do you think you're tired and dizzy? 400 or 600 calories isn't enough to keep you functioning. Don't get too ambitious and think less food is better - your metabolism could shut right down if you eat too little, and it may or may not bounce back. Talk to your nurse if you're having trouble - she may have some suggestions for you. Maybe you could split the meals up, or there are some preparation tips you could try.