BG Chap 15 - Kṛṣṇa maintains the the jīvas - by becoming the fire of digestion
The potency of vegetables, so essential for strength, health and the pleasures of our palate, is supplied by Kṛṣṇa. But even eating causes misery without proper digestion. Becoming the fire of digestion called vaiśvānara, Kṛṣṇa alone is the cause of digesting foods such as rice and other enjoyable items. He takes shelter in the stomachs of the living beings, and being engaged with the prāṇa and apāna life airs, which enliven the stomach, Kṛṣṇa brings about the digestion of the four types of food eaten by the living entities. That Viṣṇu alone is the body of the digestive fire is also stated in Vedānta. The four types of food are those which are chewed with the teeth (bhakṣyam or carvyam) such as chick peas or bread; sipped or savored by the tongue without using the teeth (bhojyam) such as soup and porridge; licked items (lehyam) such as milk rice, raw sugar and honey; and sucked items (cūṣyam) such as ripe mango and sugarcane. By His power of pervasion, and not by literally becoming the moon and the fire of digestion, Kṛṣṇa maintains the living beings.