Astanga Hrudaya
पच्यते कोष्ठ एवान्नमन्नपक्त्रैव चास्य यत् । प्रायोऽस्मान् मलतां यातं नैवालं धातुपुष्टये ॥ २१ ॥
That which is responsible for digestion of food (and bifurcation of the digested food into essence and waste), such a digestive fire located in the alimentary tract probably produces more waste (feces) from the food (in comparison to the tissues) and less nourishment of dhatus (other tissues). (The food not getting digested properly by the digestive fire in the alimentary tract gives rise to more of wastes and less for the nourishment of the Dhatus i.e. other tissues)
english translation
pacyate koSTha evAnnamannapaktraiva cAsya yat । prAyo'smAn malatAM yAtaM naivAlaM dhAtupuSTaye ॥ 21 ॥
hk transliteration by Sanscript