Vegetable diet.

I was recently given a diet that consists of Pumpkin, mushrooms, broccoli, cabbage, beans, zucchini, cauliflower, tomato, lettuce, and watermelon. Beverages - tea or water, no milk. Up to but not exceeding 1.5 lbs of each daily.
Has anyone heard of this diet or used it and if so what is the recommend time frame.