Cholecystitis is a condition caused by inflammation of the gallbladder. The gallbladder collects and stores bile from the liver, and releases it when you eat. It is needed because the liver produce bile constantly. When the gallbladder becomes inflamed, it causes right upper abdominal pain with nausea, vomiting, and fever. Changing diet patterns is important part of the treatment since the gallbladder’s function is reliant on food. You have to lose weight and have to do it slowly, so you have to reduce calorie intake (just eat less). Another important thing is reducing fat and increasing intake of fiber, so the gallbladder does not have to work hard secreting bile to digest fats in food, which reduces inflammation.