Ive been struggling with this to the point where I needed enemas to evacuate. I went off my low carb diet I had been following for months. NOt only do I feel better but I'm pooping again on a normal basis and the burping is gone way down and I just feel better generally.
Carbohydrates include fibers, which help to build up the flora. The flora generate about 80% of the body's serotonin, which among other things help regulate intestinal peristalsis.
So, I think w/o the sugar/carbs in my diet I"m just not producing enough energy in my mitochondria for the colon to have effective motility.
When I go back on the diet, I'll add in carnitine (it brings fats etc into the mitochondria) adn see if that helps the constipation and overall motility.
Adding fats will also help by increasing bile secretion, which irritates the intestinal wall also increasing peristalsis. This is why when people have their gallbladders removed they develop chronic diarrhea. The dumping of bile, instead of the normal squirting of small amounts, leads to burning of the intestinal wall from the caustic nature of the bile. This leads to an influx of water in to the intestines and increased peristalsis, thus the diarrhea.