Frequency of meals

I guess this is the most authentic allopathic view on the issue:

"The experts agreed that, as long as we do not consume more energy than we use up and we only eat when we are hungry, it may be useful to split our total energy intake into as many meals as our social pattern allows. However, the pattern of eating cannot be completely dissociated from the composition of foods consumed. Therefore within this energy intake, we must take care to consume not only a good balance of macronutrients with high carbohydrate and low fat levels, but also ensure that we get an adequate intake of essential micronutrients. "What you eat" and "When you eat it" are public health messages to communicate: frequent consumption of low energy dense high carbohydrate foods, rich in micronutrients, must be encouraged ensuring that energy intakes are not greater than energy expenditures and that eating episodes occur in a hunger state."

http://www.ncbi.nlm.nih.gov/pubmed/15806828?ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

The ayurvedic view:

"Eat when hungry, drink when thirsty"

What constitutes a state of hunger? Surely it's a signal by the body that you need to eat.
If there is no hunger signal, don't eat.
Over a period of time, depending on what you eat, a natural time cycle, suitable to you, will develop, and you would find yourself hungry at those times.
Whether that is once a day or six times a day is unimportant, and is also dependant on other factors such as lifestyle and age.
"One size fits all" is not an option here, however here are a few generalised guidelines:
A breakfast of cereal, nuts and fruit. Modify the basic Bircher Berner breakfast to suit your needs.
Lunch as the heaviest meal of the day.
Fruit in the afternoon. (Or for that matter, whenever you get hunger pangs).
A light dinner at or around sunset.
The later you eat dinner, the lighter it should be.

A common Indian alternate:

Brunch at forenoon.
Dinner at sunset.