A ct scan found that i have moderate diverticulosis in the sigmoid colon. what does this mean?

Normal: Most adults over 50, and definitely 60 in a developed country have diverticulosis. Basically this is when a small hole in the muscular layer of the large intestine allows the inner lining to protrude or herniate, forming a little sac with a narrow neck, similar in shape to a small balloon. Usually these are no problem, but may become inflamed or rupture. Stick with plenty of fluids and high fiber.

See answer: Colonic diverticulosis is a developmental condition, increasingly common with age, in which small outpouchings of colonic mucosa / submucosa protrude through small areas of colonic wall weakness. It is more common in the sigmoid colon but can occur throughout. While often asymptomatic, complications such as bleeding or even infection (diverticulitis) can occur.

Diverticulosis: Diverticulosis is essentially caused by pressure. Straining at stool causes pressure within the colon, and that pressure seeks to escape through weak points in the intestinal wall. When escaping, the pressure takes some of the intestinal lining along for the ride causing pouches (diverticuli). Low fiber diet leads to straining at stool, hence the recommendation of high fiber diet.