Hi there...slow digestion is usually related to lack of digestive enzymes, which in turn can cause constipation, gastric problems. Try having multiple short meals, 4-5, instead 3 big meals. Your schedule should also be regular. Do not starve for too long. Having plenty of water and foods rich in fibres like green leafy vegetables. Avoid foods with complex carbohydrates like sweets, oily foods and junk food. Start excercises regularly, because even sedentary lifestyle can cause indigestion. Also consult a general to rule out metabolic disorders or inflammatory diseases like crohns, irritable bowel syndrome.