अहं वैश्वानरो भूत्वा प्राणिनां देहमाश्रितः। प्राणापानसमायुक्तः पचाम्यन्नं चतुर्विधम् ॥

ahaṁ vaiśhvānaro bhūtvā prāṇināṁ deham āśhritaḥ prāṇāpāna-samāyuktaḥ pachāmy annaṁ chatur-vidham

I, having become the Fire of Life, take possession of the bodies of breathing things, and united with the life-breaths, I digest the four kinds of food.

In plain words: Krishna says he lives inside every breathing body as the fire of digestion. Working with the breath, he digests the four kinds of food people eat.