By eating 6 moderate meals a day creates the basal metabolic rate of one's body to go up, thus burning more calories. And hopefully we all know that its about burning more calories than putting in that creates weight loss. Yes, eating healthier foods with moderate fat during a bulking diet is also very important, eating more meals a day helps as well. It's not a "FAD", it's basic human anatomy.
more meals doesnt necessarily mean an increase in metabolism.
whether one is eating 3 meals or 6 meals per day, daily intake of the three macros should still be equal on eather eating plan. since meal frequency is not related at all to metabolic hormones such as t3, and since thermogensis from feeding is related to total food intake(mainly protein intake), not frequency of intake.... daily energy output would be about equal whether its 3,4,5,6,7 meals per day