Yeah...and THAT'S just the pre-op time. After that, she'll go into another couple of months wherein she can't eat much at all and will malabsorb a good deal of what she CAN eat.
OP, I know this stuff may be hard to hear. But I really hope you come back and hear it. This diet they are telling you to be on is *not safe* for you. You are in danger from this diet. Please seek a second opinion.