I think it is pretty dumb personally. If you are going to do something that drastic like a liquid diet, why not at least take in 1-1.5g/lb in protein shakes? Something you have to remember, as Rosie pointed out, when on a starvation diet, you lose a larger proportion of muscle to fat. That's why when someone that is rather large loses a lot of weight on starvation type diet, their muscle completely goes away. Then when they gain weight back, there is more fat gain than initially, since the ratio of muscle is lower. There is a school of thought out about intermitant fasting protocols, like fasting for 18 hours, then getting in your daily requirements in the other 6 hours. The problem with 2 protein shakes in 24 hrs is that's no where close to being adequate. A pretty heavy lifting and cardio workout on severly restricted starvation calories is dumb. By the end of day 2, if you go as hard as you indicate, you will probably wish you were just dead, or at least feel like it.