I switched to 5 or 6 meals per day about four weeks ago or so. It took me a while to break free of the 'big' evening meal thing, but so far, I think that its the way to go. It is a more natural way of eating. In our cultures, we are taught to eat two or three big meals each day. It upsets our metabolisms - all this starvation and oversized meals. The wrong types of carbs (high GI) at the wrong time of day and with the wrong kinds of other foods (fats) leads to extra body fat. The rush of glucose in our body kicks in the production of insulin, which signals for fats to be stored as body fat. At least thats the way I understand it (waits for real expert to correct me with hyperlinked evidence).
Eating 2 or 3 big meals, with periods of starvation inbetween is bad news for muscle maintenance and growth - they need fresh protein. Our bodies crave, and tell us to snack. Unfortunately in western civilisation, we increasingly snack on the worst possible foods and drinks. Snacking isnt wrong - its natural - snacking on junk is the problem. Then we feel bad about it - "dont spoil your dinner" is what we are told as we grow up.
If you check out body fitness and body building websites - that is the advise that you often get - eat early (a good breakfast), eat carbs earlier rather than later, eat smaller meals more often 5 to 8 times per day. Work out your calorific requirements, and depending on if you want to bulk up or lose body fat, tailor your calorific intake and protein intake sensibly.
As to changing back and forward from 3 to 6 meals per day - sounds crazy. I feel that half of the solution to weight loss is changing habits - and that can take weeks.