When: Before 3 p.m.

Why: Researchers at Bringham and Women's Hospital in collaboration with the University of Murcia and Tufts University found that individuals who ate lunch after 3 p.m. lost significantly less weight and had lower estimated insulin sensitivity (a risk factor for type 2 diabetes). Researchers also found that subjects who chose to lunch later in the afternoon were more likely to skip breakfast -- the meal that jump-starts the metabolism for the rest of the day and prevents you from stuffing your face (and spiking your insulin levels) in the afternoon.