Uttarajjhayana 16.9

16.9

no aimāyāe pāṇabhoyaṇaṃ āhārettā havai, se niggaṃthe|
taṃ kahamiti ce?
āyariyāha–niggaṃthassa khalu aimāyāe pāṇabhoyaṇaṃ āhāremāṇassa baṃbhayārissa baṃbhacere saṃkā vā, kaṃkhā vā, vitigicchā vā samuppajjijjā, bheyaṃ vā labhejjā, ummāyaṃ vā pāuṇijjā, dīhakāliyaṃ vā rogāyaṃkaṃ havejjā, kevalipannattāo vā dhammāo bhaṃsejjā|
tamhā khalu no niggaṃthe aimāyāe pānabhoyaṇaṃ bhuṃjijjā|

A Nirgrantha does not consume drink and food in excess.
Why is that?
The ācārya says: If a Nirgrantha practicing celibacy consumes drink and food in excess, there may arise in his celibacy doubt, longing, or uncertainty, or he may suffer a breach, or incur madness, or contract a long-lasting and painful illness, or fall away from the Dharma taught by the omniscient ones.
Therefore, indeed, a Nirgrantha should not eat drink and food in excess.