This might sound a bit graphic but a lot can be said about your digestion through poop. If your poop is nicely formed with a good brown color and you are pretty regular than your digestion may not be too bad. Normal transit time for food is 18-24+ hours. So if you are having IBS, diarrhea or constipation that could indicate malabsorbtion, dysbiosis, or some other gut irritation. Some people eat sesame seeds to check their transit time since it can be easily distinguished in your stools.
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.