Is consuming 800 to 200 calories a day going to get someone to lose up to 5 lbs a week?

The weight you will be losing by consuming only 200 - 800 calories a day will be muscle weight and water. By consuming so few calories your body goes into "starvation mode" and reserves the fat. The best way to lose weight is to have 3 healthy meals a day.
I read this thing on the einternet about "wieght shifting" they say it works ive been trying it myself. eating a low calorie diet dosent work because you eat the same calorie count a day so your body gets used to it and burns that much a day, so your not buring any extra. but with calorie shifting you can confuse your body and burn more calories + extra