What is the minimum amount of food that must be consumed to keep your metabolism going? Does varying amounts = varying intensities? I'm trying to get into the 5 meals/day routine here primarily for this reason but it's not as easy as it seem, especially in the portions arena. As far as that goes, breakfast, lunch and dinner I got covered but it's those in-between meals that are difficult to fill in, especially in a busy working environment where choices are slim. Can something as simple as a piece of fruit between breakfast & lunch be sufficient enough to be classified a "meal"? How about a protein shake? Considering that it's just a drink, would that accomplish anything? Thanks for your input.