The rules of food combining are mostly based on two beliefs.
The first is that, because different foods are digested at different speeds, combining a fast-digesting food with a slow-digesting food causes a “traffic jam” in your digestive tract, leading to negative digestive and health consequences.
The second belief is that different foods require different enzymes to be broken down and that these enzymes work at different pH levels — levels of acidity — in your gut.
The idea is that if two foods require different pH levels, the body cannot properly digest both at the same time.