We had an intern one summer and we took her to a Chinese restaurant on her last day. We had just sat down and she ran to the bathroom- gall bladder. She had it out the next day. When she started working with us after the fall semester, she had lost about 30 pounds. She said it part of it was the lower fat diet she said she had to eat. She's has kept the weight off and is now a doctor.
Wikipedia says that bile (which is stored in the gall bladder) emulsifies fats and neutralizes stomach acids in food in the duodenum (the tube between the stomach and intestine). It says that bile is continuously released into the duodenum instead of being stored in the gall bladder (its made in the liver) for release during a high fat meal. A high fat meal gets to the intestine and the un-emulsified fat content causes bloating and diarrhea because water is released into the intestines and the bacteria produce gas after digesting the fat that wasn't absorbed. Some patients get diarrhea for a few weeks.
To reduce the bloating and diarrhea a lower fat diet is suggested.