Diverticula usually develop when weak areas in the large intestine are subjected to pressure. This pressure on the bowel causes pouches of varying sizes to herniate outward from the colon wall. Diverticulitis occurs when a diverticulum wall ruptures under pressure, leading to inflammation and sometimes infection in that section of the bowel. Several factors increase the risk of developing diverticulitis. These factors include:

Advanced age
Obesity
Smoking
Sedentary lifestyle
High intake of animal products and low-fiber diet
Use of certain medications such as steroids and opioids increases the risk of developing diverticulitis.