The number of pounds you could gain after just one week of poor sleep.

In a recent University of Colorado Boulder study, researchers tracked sleep, metabolism, and eating habits in 16 healthy men and women. The goal was to determine how five days of sleep loss (the equivalent of a stressful week at work or school) affects a person’s weight and eating behavior. The results, published in the Proceedings of the National Academy of Sciences of the United States of America in March 2013, showed that participants who slept five hours or less per night burned an extra 111 calories per day but also ended up eating far more (especially in the evenings) than those who logged nine hours of sleep. As a consequence, the sleep-deprived subjects had gained an average of almost two pounds by the end of the first week of the experiment.