i was on the pre-op diet for 14 days and, i must say, i didn't find it difficult. i would have boost, fat/sugar free yogurt, sugar free popsicles, creamed soups (mixed w/chicken broth instead of water) and i wouldn't strain them - it'd leave the mushroom and/or chicken pieces and puree them w/an immersion blender. if you don't have one of those, you should get one - it'll make your liquids and pureed steps much easier.
i found a protein powder this weekend at wally world - it is chocolate peanut butter and two scoops has 52gs of protein!! it's made by body fortress and costs about $16. if u're this tired, u're probably lacking in protein. have u started taking vitamins? i started way before my pre-op diet - 2 complete flintstones and 1 calcium citrate w/vitamin d.
this is what works for me and is by no way perfect. we're all different and can only offer suggestions.
good luck to you - oh and 11 lbs is awesome!! i was thrilled to find out i had lost 17 that i wouldn't have to c again!!!
lori