The understanding of diverticulitis has advanced little beyond the initial postulates of Burkitt and Painter who proposed that diverticular disease results from a deficiency of dietary fiber. Diverticular disease and diverticulitis are viewed simply as a consequence of a diet, which takes in relatively little fiber. Our understanding of diverticulitis has not advanced beyond these basic concepts. As many as two-thirds of individuals in the West have diverticular disease by the age of 85 years, but only 10% to 25% will manifest any related clinical symptoms. Other than age, several risk factors have been identified for the development of diverticular disease and diverticulitis. In particular, obesity and red meat intake are risk factors. Smoking is more controversial and alcohol, coffee, and caffeine have not shown to be risk factors. Vegetable intake, a strict vegetable diet, and increased fiber intake decreases the risk of development of diverticular disease, as well as diverticulitis. Physical activity also seems protective. Despite these evidences, the risk factors and pathophysiology progression from asymptomatic diverticular disease to diverticulitis have been inadequately studied. This subject is reviewed in more detail in this manuscript.