Waste can be of seven types, according to the Bristol Royal Infirmary in the United Kingdom, creator of the Bristol Stool Chart. Also known as the Meyers Scale, the chart categorizes poop as such: 1) separate, hard-to-pass, nut-like waste; 2) lumpy, sausage--shaped stools; 3) sausage-shaped poop with cracked surfaces; 4) smooth, soft, sausage-shaped waste; 5) easy-to-pass blobs; 6) mushy stools; and 7) watery poop.

Types 4 and 5 are what you want to see in your toilet bowl. But size, shape, consistency and color are also key. Black and tarry-looking or bright red stool may indicate internal bleeding of some kind. Very pale brown, gray or white stool may signal serious liver or pancreas problems. Yellow poop may mean gallbladder problems; giardiasis, an intestinal infection; or Gilbert’s syndrome, a genetic condition that doesn’t require medical treatment.

Very smelly stool? This may mean celiac or Crohn’s disease, cystic fibrosis, pancreatitis, or that your body isn’t properly absorbing nutrients in food.