Todd, I began thinking about you again last night (don't worry...it's temporary).  

You mentioned eating a meal of meat and watermelon and having stools with undigested food the following day.  

This is exactly what happens to dogs (here I go again) when we combine meat and fruit in the same meal.  In fact, my dog will often get a real digestive upset if I forget and add fruit to her meat meal. 

I think the fact that meat and fruit go through the human digestive system at such different rates, my be affecting you.  Fruit slides through the gut much faster than the two or three hour rate for meat.  

You may want to try a meal of meat and salad, or veg and then have your fruit about three hours later - along with some protein such as a few nuts.   Probiotics should help the gut bacteria to deal with the meat better also.  

Kath