I've heard about that in terms of "calorie cycling." IE, instead of eating 1300 kcals/day each day of the week, you'd eat 1500 on sunday, 1100 on Monday, 1300 Tuesday, etc, so it averages out over time but you don't see such extreme BMR slowing.
I haven't looked into the research behind it very much- but I'm not sure. I don't think your body is really going to tell when you eat that bagel... But I do think allowing yourself a day to not be too anal about it helps, especially psychologically.