Hi Sam,   There can be many reasons for this. But sometimes eating large volumes of food quickly can be the main cause. Even thought it's hard, the best way to eat throughout the day is with small meals more often. So, instead of 2 big meals, eat 4 or 5 smaller meals. And eat slowly. Wolfing down food on the go is not healthy or good for digestion.   There is also a school of thought that eating fruits with a meal can cause this *rapid transit*. And that drinking iced water, or liquid with a meal can also cause rapid transit. It is suggested to drink cool or room temperature water. And not to drink soda or iced drinks with your meal.   If the problem continues, gets worse, or you have weight loss as well it's best to make an appointment with your doctor to discuss these problems further.   Cheers, Elizabeth