When everything is flowing smoothly, life is good. And we’re not just talking good hair days or a flawless presentation at work. Your digestive tract counts too. But when it’s out of whack, it could affect — you guessed it — the scale.

“Gastrointestinal and digestive issues can definitely have a large effect on the way we eat and how our bodies absorb and digest foods, causing us to gain or lose weight,” says Kenneth Brown, M.D., a board-certified gastroenterologist. “Most digestive problems tend to cause weight loss from poor absorption of food, but there are a few situations in which our intestinal health can contribute to weight gain.”

If the number on the scale is changing and you really aren’t sure why, one of these common digestive issues could be the culprit.