A new study shows that most Americans eat an average of 115 more calories per day on Friday, Saturday and Sunday than they do on other days. Those extra 345 calories add up to 5 extra pounds in one year. Here's how to stay lean when the bar and brunch table beckon:

On Friday scale back -- but don't go into the weekend thinking, "I can't have this or I can't have that." If your mind-set is that it's OK to indulge, you won't be as likely to binge. Can't help but splurge? Use the three-bite rule. You can't possibly blow your diet big-time on three bites of anything.

On Saturday move on. Don't be a couch potato after an indulgent night out. Instead, take a long afternoon walk or a bike ride to destress and burn off any extra calories you've consumed.

On Sunday stock up on healthy stuff. Plan nutritious meals you enjoy for the week ahead, and you won't miss the fattening foods. (Infact, you'll probably welcome the healthy change!) Buy a whole-grain breakfast cereal, fruit to slice up for lunch or nuts to snack on when that 4 o'clock slump hits.