Uncomfortable topic, but I can relate. I never have gone 5 days without. I go daily, but it was taking me, well, 15 minutes to go, if you know what I mean. I blame it on all the processed foods I was eating. For a few months I tried to do my own version of Jenny Craig were you eat pre-packaged dinners, to control your portions and for easy calorie counting. Well that kind of food is devoid of any fiber, and it was killing me "down there". Now my doctor wants me to have a colonoscopy which I dread but will get anyway. As for my constipation, I have it under control finally. I found OTC fiber supplements useless and ineffective. What finally did it for me was adding 2 foods daily to my diet. Legumes and prunes. Real modern remedies. ha ha Legumes and prunes are wonder foods for your insides.
I eat one cup of beans every day - alone, in a soup, or on a salad - as my first meal. Then sometime later in the day I eat 5-6 prunes. This has cured my problem. Probably adding fat to one's diet would help too. But there is a big calorie price to pay for that.