A worrying new study indicates that people who are considering gastric bypass surgery should be aware that even though it may result in an immediate loss of weight, it can greatly affect your eating and digestion down the road. The study, which involved 544 obese adults, found that about two years after the start of the study they often complained of indigestion, abdominal pain and dumping syndrome, or a rapid emptying of the stomach.

The study found that about 71 percent of the gastric bypass group couldn’t eat foods like red meat and anything high and fat or sugar, compared to 17 percent of those who had not had the surgery. There didn’t appear to be any link between the total amount of weight lost and these issues, however.

It’s an alarming finding that shows that there are much bigger consequences to gastric bypass surgery than the immediate aftermath. The surgery has been an effective way to combat extreme obesity by shrinking the stomach and then reconnecting the small intestine.

The study is titled, “Gastrointestinal symptoms and food intolerance 2 years after laparoscopic Roux‐en‐Y gastric bypass for morbid obesity.”

“At 2 years after surgery, patients undergoing LRYGB for morbid obesity have more gastrointestinal complaints than obese controls,” the study states. “Food intolerance is a common side‐effect of LRYGB independent of degree of weight loss or the presence of other abdominal symptoms.”