Saliva generally contains digestive enzymes such as amylase, protease and lipase. Saliva is a liquid secreted by oral mucosa, which is an important part of human body. It can moisturize the mouth and remove oral odor. Saliva contains digestive enzymes such as amylase, protease and lipase, which can help food decompose and promote food digestion and absorption. Everyone's saliva contains digestive enzymes.

There are biological reasons for people's thinness, such as thin figure and pathological reasons, such as malnutrition, endocrine system diseases, digestive system diseases, malignant diseases and so on. And thinness is not caused by more digestive enzymes in saliva.