Bhagavad Gita · Dhyana Yoga (Atma-samyama Yoga)Chapter 6, Shloka 16 (6.16)

Two "excesses" — both obstacles. Eating too much and not eating at all; sleeping too much and staying awake too much.

Shankaracharya — "one's own measure". Ātma-saṃmitam anna-parimāṇam atītya aśnataḥ — one who eats beyond the amount of food suitable for oneself; and na ca ekāntam anaśnataḥ — one who does not eat at all. As evidence, a shruti statement (Shatapatha): yad u ha vā ātma-saṃmitam annaṃ tad avati tan na hinasti, yad bhūyo hinasti tad, yat kanīyo'nnaṃ na tad avati — food in one's own measure protects and does no harm; more than that harms; less does not protect. An alternative: the measure of yoga texts — … sa-vyañjanānnasya tṛtīyam udakasya ca, vāyoḥ saṃcaraṇārthaṃ tu caturtham avaśeṣayet — (taking the stomach as four parts) two parts food with accompaniments, the third water, and the fourth left empty for the movement of air.

Acharya Ramanuja. Atyaśanānaśane yoga-virodhinī — both overeating and fasting oppose yoga; ativihāra-avihārau ca — too much moving about and none at all; atimātra-svapna-jāgarye — too much sleep and too much wakefulness; atyāyāsānāyāsau — too much exertion and no exertion at all.