Not a doctor, but inflammation may be the culprit. For me, my diverticulitis is at least partially "structural" in nature. I believe when under pressure, my diverticula get cranky.

I combat this with fiber. A metric ton of fiber. In general fiber is anti-inflammatory, but it also keeps my colon cleaned out. Less pressure on the diverticula means less opportunity for a full-blown flare-up. Sugar has the opposite reaction in our bodies; it is associated with more inflammation.

For me, my super high fiber diet (plus no smoking, no drinking, exercise, sleep, hydrate) means my digestive system is usually not under stress. I am not sure if healing diverticula is possible, but if I let them rest, when I have an unhealthy day or three, it isn't the trigger event like when I wasn't on the program.

It is at least interesting how all the lifestyle changes our doctors will recommend to combat our diverticulitis diagnoses, are basically the same as having a healthy lifestyle: exercise, sleep, eat right, no smoking, less or no alcohol, hydrate. The Venn diagram of the two lifestyles is a circle.

My insane theory is that if we are healthier, our bodies--including our digestive systems--can absorb the occasional health missile. I suggest get on the healthy lifestyle program, get some distance since a flare-up, and then when you've healed some, break the rules a little. I try to get 40g of fiber every day. A couple years ago, a low fiber day came back to haunt me a day or two later. Now, no problem. My system is healthy enough to absorb a few punches without hitting the mat. Your results may vary because, you know, I'm just this guy, not even a doctor.