Many plans suggest eating three meals a day (breakfast should be eaten within one hour after you get up) then three additional meals/snacks.
An article on Medicine Net has more information on the pros and cons of eating more than three meals a day. You can read the article here
I have found that three meals and two snacks of under 100 calories with an additional low calorie snack in the evening works for me.
Rather than finding that I have a limited number of calories left at the end of the day, I have worked out the approximate amount of calories to eat at each meal.
Breakfast – 250
Mid-Morning snack – 100
Lunch – 250
Mid-Afternoon snack – 100
Dinner – 450
Evening snack – 50
This totals 1,200
Today I stayed within 1,200 calories and worked in the garden this evening for an hour and a half. My pedometer totalled over 12,000 steps which is approximately 6 miles. I use the stairs instead of the elevator during the day and the steps soon add up. It's only been four days and I have so much more energy and by limiting processed food, I no longer have that stodgy, overfull feeling.