I thought that if you only ate 1 or 2 meals a day your metabolism would slow to a crawl. If you eat smaller, more frequent meals, your body "knows" it doesn't need to store the energy you consume, and can burn it off. Yes, your digestive system stays "on" most of the day, but only at a low level and it keeps your body from storing everything you eat as fat. The book "Younger Next Year" is very good on this topic (and very humorous as well). It goes into a lot of the recent science on the topic.