What the experts keep missing is that you aren't supposed to quit. This is supposed to be for life even if your carb intake on maintainace will be higher than it was (at least for most people) during the weight loss phase. Of course, if you go off ANY diet and go back to your old eating habits that got you fat in the first place, you're going to gain the weight back. It's not rocket science, but yet all these experts seem to keep missing the obvious.
It really scares me that these experts that answered the question from that lady in her 70's who wants to gain weight are advising her to eat more sugar (ensure, jam, juice, etc...). Are they trying to turn this poor lady into a diabetic??? Yikes!