Sorry for the gross question. But I think this is sorta fascinating. 8-) 

Did you know that in general, the faster your metabolism, the more you poop. Those with a slower metabolism may not visit the bathroom twice a day. They may only go once a day or once every other day (or even more infrequently). Regular exercise, a healthy sleep schedule, and a clean, whole foods based diet will keep your metabolism going at a steady pace—and keep you going to the bathroom regularly.

That said, digestion and metabolism aren’t as closely linked as it may seem. What you eat can affect how quickly your food moves through your body, and just because something moves through your body rapidly, that doesn’t necessarily mean you were able to efficiently utilize the energy from that food (which is what a healthy metabolism’s all about). Also, things that don’t directly relate to digestion—like your age, gender, weight, current exercise routine, health issues, and even your hormones—can affect your metabolism.