Yes the celery is stringy, that is why for the first few months it is a no no.  It can be hard to pass out of the pouch.  Mac and cheese is ok, but I would wait a month or two before you really get back into carbs.  If you stick with the dr. diet you will loose quickly.  The first few months are key because it become harder to loose as time goes by.  You can use non fat, low fat or regular cheese if you like.  If you are not as active as most, I would suggest low fat or non fat.  If your stomach can handle it, alittle regular could be ok.  If you are ready for meat, try Wendy's Chili with some string cheese.  that one helped me alot with the protein.  Try alittle and see if you can handle it.  Some people can't eat meat ever again, others do just fine with it.  It is sort of a trial an error.  Mexican food is fine, later.  Avoid the chips and bread if you can.  I would still wait awhile.  Avoid fried foods!!  Both for weight and for dumping.  Again this is a tool,  Use it to your advantage...Brian in CA