I recently started this diet. I haven't had too hard a time, but it is definitely hardcore. About 800 calories max... 13 oz of protein a day (for me) and two servings of low carb vegetables. You have to do it while under the supervision of a dietitian and a doctor though... need a battery of tests initially to make sure your body will handle it, then more tests periodically throughout your diet.
Have actually been blogging about it myself to try and keep on track and motivated.
thisismyjourneytothin .blogspot .com (w/o the sapaces of course)