Diverticulitis is a condition where pouches in the intestinal tract (diverticula) become inflamed or infected. It often develops after diverticulosis, a common condition where diverticula form harmlessly in the intestines, especially in those over 60. A diet low in fiber over many years can cause diverticulosis due to stripping of fiber from processed foods. Mild diverticulitis is usually treated with rest, diet changes, and antibiotics, while more severe cases may require surgery. The diverticulitis diet focuses on fiber and avoiding foods that may irritate the intestines during recovery, then transitions to a long-term high fiber diet to prevent future occurrences.