3B: You begin with mechanical digestion in your mouth, where starches are also broken down. The bolus of food travels down your esophagus into the stomach, where it sits and churns, further allowing for breakdown of biomolecules like fat and protein.The contents of the stomach then enter the small intestine, which is where the bulk of digestion and absorption of nutrients occurs through the work of shear mechanical (peristalsis) and chemical (digestive enzymes) force. Then our food commutes through the large intestine (AKA the colon), where most of the fluid absorption in the GI tract occurs. Phew! Eating sure is a lot of work! By Raja Narayan.