My wife and I have been loosely following a Zone diet for about 6 months - mainly because we like the food. There is a Zone book titled 'The Formula' which contains a number of great snacks (and meals) for during the day, or late night - often they include fruit, cottage cheese, etc., but there are even some unique ones like peanut butter yogurt and nutty sweet yogurt. They're all quick and simple to make.
We really like the Zone (basically eating balanced 40% carb, 30% protein and 30% fat). We feel healthier and we've both lost weight using it. We also have 2 small children and they love some of the recipes too - especially the breakfasts like strawberry smoothie and Oatmeal w/Blueberries (this last one's from a different Zone recipe book).
I noticed several folks exercise in the early AM like I do. If you follow the logic of the Zone diet - which is all about balancing your diet to avoid insulin spikes - you should have a little nosh in the morning before working out - maybe half a snack portion. I usually just have 1/3 of my breakfast and then eat the rest after my workout. I find this really helps - especially when I'm doing a workout of 1 hour or longer.
Peter
PS Even though I know it's probably sinful, I've found I can have a sweet and glass of milk late at night (like 1 Twix bar) and still lose weight. As long as I'm good the rest of the day and exercise regularly.