I too have done Scarsdale. It is a very strict diet. I may not be much of a breakfast eater, but I need more than half a grapefruit and a slice of "protein toast" -that is barely 100cals! It is recomended that on follows the strict diet for 2 weeks, followed by 2 weeks on the "Keep-Trim Eating Plan"(KTEP) and so forth and so on, til you reach your goal.
KTEP is reasonably healthy and I believe one could stick to it for life:
Eat freely: Fresh fruits (limit bananas), vegetables, (limit corn and peas), eggs, cheeses (all kinds), lean meats/poultry, fish/shellfish,artificial sweetners.
Eat in moderation: Skim/low fat milk, oilives, walnuts, pecan nuts, bread (no more than 2 slices/day, or equiivalent. 100g potato or sweet corn =1 slice bread)
Not permitted:Fats & oils, sugar and ANY food product containing added fat or sugar, avacadoes, nuts other that walnuts/pecans.