When I was about 15 (a long time ago) I found an "ice cream diet" in Family Circle. No kidding. There were menus for every meal, and the cornerstone was 1/3 of a pint of ice cream a day. I was too young to get a job, so I put my whole family (my mother, father, and myself) on it for the summer. I did a LOT of cooking, and buying all that ice cream in PINTS so that I could cut an exact measurement for dessert just made them all laugh.
Mom was getting her Master's Degree and Dad was teaching for the summer, so they didn't have to worry about meals. I'm sure that they snuck food when I wasn't looking, but we all had fun and lost some weight in the process. Kept me out of trouble, doing all the planning and shopping, although I struck up a romance with the butcher's helper!