Stool volume is a factor of fiber, bacteria in the colon and water.Storage time also can effect things, as does speed through the GI tract.If the rectum is hypersensitive and you don't ever store stool for any length of time at the end it will be lower volume than if you have more normal evacuation (so if you go 3-5 times a day with normal stool consistency rather than loose they will be small in volume as your rectum won't wait until you have a normal volume accumulate before sending it out.If you tend on the constipated end of things you can have low volume because all the water is sucked out of it. Think of a bowl of jello. If you leave it out and uncovered and let the water evaporate it eventually takes up a lot less space.I don't know how much fiber you eat, but even a well-balanced diet may not have all that much fiber in it depending on what you choose and how much fiber you tolerate. If you tend to the too fast end of things besides not having as much storage time at the end, it may not get as compressed along the way so be a low volume.Low volume stools are not a specific symptom of any disease but will be seen in everything that causes constipation or diarrhea.