The researchers suggest that what's going on is that the genes that regulate our metabolism aren't turned on fully at certain times of the day (like late at night when we should theoretically be sleeping). "Every organ has a clock," said lead author of the study Satchidananda Panda. "When we eat randomly, those genes aren't on completely or off completely." So during the day, when we're moreactive, our metabolisms are more fully "on," and therefore able to processesenergy more efficiently. The authors do caution that we shouldn't feel that we have license to eat whatever we want during a window of time as long as we fast after the sun goes down. "What we showed is under daily fasting the body can fight unhealthy food to a significant extent," says author Megumi Hatori. "But there are bound to be limits.